Feliks-Audio ENVY Performance Edition Review – A High-End Masterpiece?

Sometimes we test decent-sounding headphone amplifiers; other times, we try great ones that leave a positive impression even weeks after sharing our thoughts. But rarely do we find amplifiers so exceptional, achieving legendary status among headphiles, that we feel compelled to purchase them after the review period ends. Sadly, such units are tested once or maybe twice a year, and I lament that the very best units aren’t destined for the masses, requiring a substantial investment once you venture down the rabbit hole. The amplifier I will be testing today doesn’t break the bank compared to those made from unobtanium, having the right price and feature set that I cannot wait to put to good use.
Testing big, bold, and ballsy tube-based headphone amplifiers is not new around here. The $15,000 Trafomatic Primavera was an ear-opening amplifier, especially in terms of effortlessness, soundstage size, depth, and holography, so much so that we were compelled to buy not one, but two units for ourselves and then take an audiophile leave for a couple of weeks to fully immerse in never-ending nirvana-reaching sessions. The €8,000 Cayin Soul 170HA that we purchased a couple of months ago for its unlimited power and headroom, and quite possibly the best dynamics we’ve ever experienced via headphones, is still undergoing tube rolling experiments. Luckily for you, this time around we have a smaller, much easier-to-carry-around amplifier that also doesn’t require selling a kidney and a half, priced at €6,999 as I’m typing this.
The mighty ENVY from the world-renowned tube amp manufacturer Feliks Audio is always turning heads at various HiFi shows. We’ve written about it countless times as it’s often used by headphone makers as an end-game amplifier, whether dealing with current-hungry planars or high-impedance dynamic headphones. I’m also glad to inform you that our ever-growing amplifier arsenal is increasing with the rad-looking ENVY Performance Edition in a stunning Zebrano finish, which fits well with both my office head-fi battle station and the main HiFi gig.
If you’re reading these words, you already know that good old Sandu won’t deliver the “standard 5-page review” that you can find on every corner of HiFi without talking about tube rolling, preamp capabilities, or doing a proper photoshoot. Nah, we’re different, and we’re proud of this! We’re going all-in, 200% more precisely, so expect anecdotes, tales, and a journey that you’ll hopefully enjoy.
To tell the full story, I was always looking with envy at the Envy at various shows—the finish, the smooth lines, the exquisite aesthetics, the golden standard (300B with 6SN7) in tube amplification with solid-state rectification to fully preserve the speed of sound and its resolving abilities, getting the best of both worlds. I’ve always found it to be sharp and elegant at the same time. Some of you may not pay much attention to perfect symmetry in everything, but I try to have it everywhere in my day-to-day life. Approaching the Feliks Audio booth at the Audio Video Show in Warsaw last year (our full report can be found here), I started a casual discussion about headphones, amplifiers, and whatnot with Michal Feliks, one of the brothers from the big Feliks family. We have known each other for a couple of years now, but, for some reason, I never had the chance to try their hand-crafted amplifiers.
Fast forward a couple of months and a familiar face calls me and asks for help in delivering a heavy-duty package to my front door. Said and done, I put my back to good use. The Feliks logo on the side of the cardboard box already spoiled the fun of opening an unknown package, but wait! My face was brighter than the sun that day, as finally, the mighty Envy would be put to good use with one of the best headphone test benches, driving a couple of world-class headphones, tested by a Golden Ear certified guy. What could possibly go wrong?
But wait, don’t turn the page yet! This is not your regular Envy that already demands unloading your yearly savings and at least a gold ring for your beloved. I will be testing the pimped-out Performance Edition that swaps the meh-sounding Electro-Harmonix 300B Gold tubes with much better Full Music 300B power tubes, and more importantly, the internal point-to-point wiring is now done with single-crystal copper signal wiring (UPOCC). This adds an extra €800 expense, fork out an extra €800 for a Zebrano finish, and we arrive at an €8,599 little monster. Today I will be discussing what I believe is one of the most magical-sounding amplifiers you can get right now for non-electrostatic headphones. It’s one of those units that made me question everything I know about audio, and before going down the rabbit hole, let’s ask some (tricky) questions to none other than Łukasz Feliks, the main face behind this masterpiece.

Q&A with Łukasz Feliks of Feliks-Audio:
Q1: Let’s travel back to the dawn of Feliks Audio. What moment sparked the creation of this incredible brand? Is amplifier design and a passion for music running wild in the family?
Feliks Audio is a family business, started by our father, Henryk Feliks, in the 1990s after the Iron Curtain fell. Our father is an amazing electronics engineer and music enthusiast, and he has been putting his heart into this for all these years. About eight years ago, the second generation (i.e., the three sons) took over running the business, continuing the passion and expanding it to a more global reach. We are a premium audio boutique, with no desire for mass-produced cost-competitive “appliances.”
Q2: The case, those smooth curves, and the serial number plate with your names on it—pure elegance! Can we give a shoutout to the mastermind behind this stunning creation? A round of beers on us!
Feliks is managed by the three brothers, and each of us brings something unique to the business. Piotr is an engineer who follows the path our father started; he now leads our R&D and production. I am responsible for business development and sales, while Michał, a skilled graphics designer, is responsible for the external design of the amplifiers and our brand visuals. Hence the beer goes to Michał in this case! 🙂
Q3: The Envy certainly stirs a lot of envy among the competition! It’s a beauty from every angle. Just how much time went into bringing it to life from the first spark of inspiration to the finished product?
It’s hard to quantify at this point, but the original Envy design took us over two years. What’s interesting is that we continue experimenting with new technologies to offer new unique finishes. An example is the “real” black piano finish (done by a world top-tier piano refurbishment company) that we used for the Anniversary Edition Envy, which shows we never stop thinking ahead, even when it comes to aesthetics.
Q4: How does the Envy stand out from other models in your lineup? Any special features we should know about?
It was planned from the very beginning as the flagship—the one amp to rule them all. The focus was on providing the best possible sonic experience for the broadest selection of headphones. Before Envy, we focused mainly on OTL (amplifiers without transformers on the output) designs, which are fantastic for dynamic headphones and easier-to-drive planars. With Envy, we wanted to challenge the most difficult headphones to drive (e.g., Susvara). One interesting feature is the design of the balanced feature: it is a SET (single-ended) amplifier, yet it is still balanced, as we use synchronizing transformers (made for us by Lundahl in Sweden) for each channel.
Q5: The Envy is a rebel amplifier, shrinking in size, reducing power draw, and most importantly—shattering tube amp sonic stereotypes! Was this a deliberate “screw it, we’re doing things differently” move, or did it just happen naturally?
That was the ambition from the very beginning. We know there is no “end game” in this hobby, but we wanted to make something pretty close to this cliché. The 25th Anniversary Edition last year, which could be called a completely new creation, was an even bigger demonstration of this ambition.
Q6: We’re curious: Are you experimenting with different power and driver tube combinations for upcoming amplifiers? And what do you think about vacuum tube rectification for the future? With today’s best headphones being incredibly hard to drive, could the KT150 or KT170 tetrodes be the magic solution?
We always have a few prototypes in the pipeline. Although retired, our father never stops working with Piotr on new concepts. However, for headphone amplification, there are certain favorites, and the 300B is among them for being very musical with low noise levels. In our opinion, the KT150/170 has more place in powerful push-pull configurations for 2-channel audio but is not a great headphone tube. Another interesting tube we might use at some stage is the 2A3, which has half the power of the 300B yet very favorable sound characteristics.
Q7: Amplifier designers often tweak their creations using several pairs of headphones. What specific headphones did you use to fine-tune the Envy? And what’s your go-to set of cans that you keep coming back to for that sweet sound?
Using multiple very different headphones usually yields the best results and most representative “customer satisfaction.” Of course, in the case of the Envy, we spent countless hours with the Susvara, but also other tough planars like Abyss 1266/Diana or more recently the Immanis. My personal favorite remains the original Susvara, and paired with the Envy it’s just an unreal combo.
Q8: Can you share a memorable moment from the workshop while crafting one of your amplifiers? Perhaps an unusual request for a custom amplifier that made you think: “Now that’s interesting!”
Yes, at some point we began to see a lot of Envy customers, who of course love tube rolling, reach out to a small German manufacturer Elrog, and use their 300B tubes. We received some samples of their tubes and were impressed as well. This gave us the idea to use these low-volume tubes, with our own brand markings, to celebrate the 25 years of the company by building the Anniversary Edition of Envy in 2024, using the ER300B Elrog power tubes. Also, many of the available wood finishes are the results of customer requests which we all loved and decided to commercialize. This is the power of advanced boutique operations: we can be flexible and agile while never sacrificing quality.
Q9: If Feliks Audio were to dive deeper into the HiFi stereo world, what type of amplifiers and/or preamplifiers would you love to create from scratch, besides the Arioso 300B, which seems like a perfect match for sensitive loudspeakers?
We are actually working on some 2-channel options. One of them is a power amplifier that could be matched with one of the headphone amps (in a preamp role). Such a power amplifier could operate as a monoblock or two monoblocks and use KT150 as the power tube.
Closing Words: Thank you for this exhilarating Q&A session! We can’t wait to see (and hear!) what Feliks Audio is cooking up next. Keep the internal fire blazing and the tunes playing!

Design & Build Quality
Some of my brothers-in-arms around here don’t pay much attention to the looks of the gear they’re using, but for me, this is a delicate matter. After a certain price point, these items are no longer HiFi components; but pieces of modern furniture. They need to blend in and look nice on a shelf filled with records or on a HiFi rack alongside equally impressive components. More importantly, the discerning eyes of our beloved should appreciate them too.
There’s another important aspect: I like having symmetry in everything I do, including my HiFi systems. Misaligned screens or oddly designed cases aren’t taken lightly around here; I prefer it when I can frame my shots perfectly in pictures and videos. Everything needs to meet my expectations, and I’m glad to report that the Envy, finished in this beautiful Zebrano wood, is not only perfectly symmetrical inside and out, but it’s also the most stunning headphone amplifier I’ve ever laid eyes on.
Honestly! Just look at it and tell me if it doesn’t ooze style, refinement, and badassery. The white princess, Trafomatic Primavera, still looks great, but its finishes aren’t as masterfully crafted as those on the Envy. The Cayin Soul 170HA, on the other hand, features a similar style, perfectly combining metal and wood in harmony.
The moment you start turning the Envy around is when you realize how much thought was put into making it beautiful and practical. Heat dissipation is always an issue with transformer-powered tube amplifiers biased into Class A operation, but this time around, I see many cleverly positioned spaces through which hot air can escape outside its enclosure. Even after an 8-hour listening marathon, I found it only warm when touching the wooden accents. Armed with a Bosch infrared thermo detector, I recorded 42 degrees Celsius at the hottest point (just below the power transformers) on the side panels and 53 degrees Celsius on the metal cage surrounding the power transformers. Considering these temperatures are within safe limits and far away from the critical analog components, the Envy should live and prosper for a very long time.
I don’t think I have ever encountered such neat-looking wooden feet and foam inlays that absorb micro-vibrations, surrounded by tiny holes that help move hot air outside its case. This is both clever engineering and a cool aesthetic at the same time.
I don’t know why, but I’ve always had a penchant for large-volume knobs that aren’t easily turned. Don’t ask me why, but there’s something magical about slowly turning up the volume with gentle force, like supercharging your listening experience. The clicky gain and input selectors are also very satisfying to push left and right, but the big matte-black volume wheel takes the crown. Did I mention that the On/Off function takes the form of a touch surface with the Feliks Audio logo embossed? It adds a twist of modernism to the oldest form of signal amplification, propelling Feliks Audio into the 21st century.
Long story short, the moment I placed it on my desk, I couldn’t take my eyes off it for the next two hours or so. I kept turning it on all sides, trying to understand how they seamlessly blended its inner workings with modern design, prioritizing heat dissipation. So far, this is the coolest operating high-end vacuum tube-based amplifier we’ve tried, and it’s already started to grow on me.

Controls & I/O
Since we’re discussing an analog input-to-output headphone amplifier and preamplifier, you won’t find a lot of features, a display, or a complicated layout. This is a straightforward, set-and-forget type of amplifier that won’t confuse you with numerous switches or hidden menus. On the front panel, you’ll find a balanced 4-pin XLR and a single-ended 6.35mm headphone jack. An impedance and input switch are located on the right, and a massive volume knob sits exactly in the middle, with everything else moved to the back.
Since it can function as either a headphone amplifier or a preamplifier, you’ll also find a pair of RCA and XLR inputs and a mirrored symmetry of analog outputs. An AC inlet, a voltage selector (230V or 115V), and a serial number are the last features you’ll see there.

Under its Hood
We are dealing with a beefy single-ended transformer-coupled Class-A headphone amplifier that outputs 8 Watts per channel into 16 Ohms at THD >5%, and 5 Watts per channel in the same load with THD ⩽1%. This isn’t just an incredibly powerful tube amplifier; but one of the most powerful headphone amplifiers I have tested around here. It constantly draws 110 Watts from the wall, regardless of the selected volume level.
A single-ended amplifier is a type of amplifier that uses a single triode to produce an output, in contrast to a push-pull amplifier, which uses a pair with antiphase inputs to generate an output with the desired signals added and the distortion components subtracted. Single-ended amplifiers usually operate in full Class-A, while push-pull amps typically operate in Class-AB or Class B, consuming considerably more power compared to other designs.
The benefit of such analog designs is simplicity! There isn’t a simpler amplifier design out there. You have a driver tube that provides voltage output, coupled to a triode, which is then directly connected to your headphones through an audio transformer in a common cathode arrangement. The triode is biased into Class A operation by applying a suitable negative bias voltage to its input control grid or by raising the cathode potential with biasing components.
The Class-A working principle is known to have the best sound quality, but such amplifiers will cost you several times more, as about 75% of the consumed power is transformed into heat that is never utilized. This necessitates tripling or quadrupling the number of components and case size for similar output power compared to a Class B amplifier. In such designs, vacuum tubes are always powered on, producing the lowest possible distortion and providing maximum amplitude to the output signal. The same amount of current flows at the output, even if there isn’t an input signal; therefore, large heatsinks and/or heat dissipation fins are mandatory. As you can guess, the efficiency of such amplifiers is very low, typically around 25%.
I don’t want to complicate things, but in simple terms: most tube amp manufacturers use negative feedback to bury the noise floor as deep as possible, which is easy to do, albeit at the cost of a less natural presentation. The more challenging part is crafting a zero-feedback amplifier that doesn’t raise noise and distortion to dangerous levels. Zero-feedback amplifiers are usually regarded as the purest, most natural, and life-like sounding units available. Since there is no way to manipulate the noise floor, Feliks Audio lowers it by using the highest-grade components, including custom-made parts.
As for the tubes themselves, the Envy uses a set of current production PSVANE CV181-TII double triodes and also accepts any other variants of 6SN7/GT or 6N8S tubes. These are easily the most loved double triodes worldwide, and luckily for us, there are still many manufacturers producing these tubes. If you want an extra dose of sweetness, you can always try some NOS tubes—just make sure to have them in matched pairs. The power tubes are also quite special; there aren’t audiophiles who didn’t try at least one 300B-powered unit during their journey. As with the 6SN7, numerous manufacturers are making these, including high-end variants that come at a pretty penny, from the likes of Western Electric, KR Audio, Takatsuki, and ELROG. Lucky for you, I have a substantial collection of 6SN7 tubes and several 300B variants, and in the latest chapter of this review, I will be testing each one of them so you can save a few bucks by choosing the right pair.

Test Equipment
Before you ask, the Feliks ENVY Performance Edition was primarily used in a head-fi battle station as a headphone amplifier, but I also utilized it as a preamplifier in a well-thought-out stereo rig.
This is an end-game headphone amplifier, which is why it was imperative to use as many high-end headphones as possible, ranging from dynamic to planar-magnetic types, available in both closed-back and open-back configurations. For the sake of science, I will also test its noise floor with a few ultra-sensitive IEMs, but most of my testing will focus on a pair of HiFiMan Susvara Unveiled, Susvara OG, T+A Solitaire P, and Sennheiser HD800S.
In the living room, the Rockna Wavedream Signature DAC ($18,000) received input via I2S from the Rockna Wavedream NET 4 TB Roon server ($11,000), followed by the Feliks ENVY (which replaced a Chord Ultima 2 PRE) controlling two Chord Ultima 3 monoblock amplifiers ($15,900 each). Raidho TD2.2 loudspeakers ($49,500) were my speakers of choice, playing tunes for almost two weeks before I made my final evaluation. All cabling used was from the Crystal Cable Monet range (power, interconnect, Ethernet, and speaker cables). Everything was also powered by a KECES IQRP-3600 balanced power conditioner.
Everything should be as clear as the blue sky, so what are we waiting for? Let’s hit some eardrums!

Sound Performance
I. Prologue
If you’re already saving pennies for an amplifier of these proportions, there is one important thing you should also do after cracking open the cardboard box: arm yourself with lots of patience, as a very long burn-in process will begin. This particular amplifier was delivered in December 2024, just a couple of days before Christmas, and since I already planned our Christmas and New Year’s trips in advance, I left the Envy in the capable hands of a fellow head-fier who is as passionate as I am.
On my way to the mountains, I was constantly exchanging messages, as I was probably more curious about Envy’s sound than my buddy listening to the darn thing at home. He wasn’t impressed; he even called it bright-sounding, mentioning a weird resonance around the upper midrange and lower treble. This shouldn’t happen, I told myself, given the 300B + 6SN7 combination that many believe is the gold standard of tube amplification. It should sound more like Mother Nature rather than like a screechy ChiFi amp. Clearly, a very long burn-in was needed to fully unleash its potential.
In the following days, I sensed a different tone in the messages we exchanged; the majestic bass finally paid him a visit, but the sound still felt a tad off and not as tubey as one might expect. I finally arrived home, picked up the amplifier, and began conducting some experiments of my own. Armed with eight different pairs of 6SN7 driver tubes in both NOS and current production variants, including several 300B variations, I spent days trying each tube and assessing its performance. I, too, noticed a slight unpleasant ringing, as if the sound was a bit aggressive and not as effortless as one might expect from an amplifier of this caliber.
After toying with both power and driver tubes, it became clear to me that the stock PSVANE CV181-TII were adding the unpleasant ringing, making the sound more solid-state in nature, rather than the tubey character I expected. There’s a new kid on the block who offers both 300B and 6SN7 tubes that I thought were worth checking out; you might have heard about them: Ray Tubes. I had several of their 6SN7 variants, including their top-tier 6SN7 RESERVE, which sounded just as technical and clean as the stock PSVANE tubes, but without the extra harshness.

II. Preliminary Sound Impressions
Having at our disposal two headphone amplifiers that could deliver a bit more power (twice as much if we consider the Cayin Soul 170HA), I was initially skeptical that a two-times lighter amplifier could pose a threat to the dynamic duo we know so well around here. I wasn’t convinced that the Envy could fully drive some of the most demanding headphones I am familiar with; when power isn’t reaching for the stratosphere, that usually signals a weaker dynamic range and a less impressive overall performance.
However, let’s not forget that neither the Primavera nor the Soul 170HA uses the legendary 300B power tubes, nor do they employ solid-state rectification, and at this point, I was prepared for anything!
The burn-in is finally over. I finished my coffee and my morning routine, and the Envy now has more than an hour of playtime for today, inviting me for a long listening session. I know many of you consider the PSVANE VC181 to be quite resolving and neutral, and yes, I will confidently say that they add a bit of solid-state flavor, at the cost of not being as sweet and lush as I desired. A second later, a pair of Sylvania Bad Boy 6SN7 found their way into the amplifier. I let them warm up, and voila! All the midrange presence I could ever dream of, a huge soundstage stretching in all directions, and an overwhelming sweetness that the stock tubes simply lack.
Sure enough, the resolution took a small hit, and so did the noise floor, but I kid you not: the rewards far outweigh the cons by a considerable margin!
I’m a little sad that not a single Envy review has mentioned tube rolling, as, after toying with it for more than two weeks, I don’t know of any other tube amplifier that changes its tonality so dramatically with just a tube swap. With the Primavera, it was a matter of fine details; both the driver and power tubes sounded incredibly similar. The Cayin changes its tonality by a significant amount more, but let’s not forget that, regardless of which tubes you roll, the KT170 tetrodes can’t currently be replaced with third-party options, meaning you can only partially alter its voicing.
The ENVY, however, is a tube roller’s dream!
If you get the standard edition with Electro-Harmonix Gold pin 300B and PSVANE CV181 tubes, I wouldn’t be surprised if it still sounds a little grainy and hotter up top after the burn-in period finishes, as opposed to lush like previously mentioned amplifiers would. Swap the driver tubes with NOS variants – some of which can be incredibly affordable (Raytheon 6SN7 is a very good example), and pair them with Western 300B variants, and the sound will be at poles apart from the standard configuration.
As for me? Well, I paired a set of new-production Western Electric 300B tubes with the craziest 6SN7 tubes ever produced: the KEN-RAD 6SN7 Black Glass. Craziest? You need to hear these on modern tunes and bass-intensive tracks to fully understand what I mean. Dynamics doubled their oomph, and the bass really pumps some iron compared to the stock PSVANE, becoming noticeably stronger and more layered, further enhancing its qualities.
My dear readers, the Envy is not an ultra-linear, almost solid-state-sounding tube amplifier. That’s a common misconception, but it might be accurate if you’ve never handled those tubes. This is, by far, the most chameleon-like sounding amplifier I’ve used in recent years, as you can tailor its sound to your preference. Given the unlimited number of 6SN7 and 300B variants available, I’m confident that there won’t be two ENVYs that sound the same.

III. Background Noise & IEM Compatibility
Let’s be serious for a second: you aren’t buying a ~15-kilo (33-pound) monster of an amp to drive tiny IEMs, are you? I don’t feel safe connecting ultra-sensitive IEMs to an 8000 mW-per-channel beast when a single mW is all that’s needed to reach super loud levels. What could possibly go wrong with multi-thousand dollar IEMs… right?
We don’t have a gain switch on the Trafomatic Primavera or on the Soul 170HA, and seeing such a switch on the Envy brightened my day. The gain varies substantially on the Envy depending on the setting, and let’s not forget the output impedance, which sits much lower at its lowest gain position (3.8Ω versus 20Ω on the high-gain setting). If we consider the rule of eights (the output impedance of the amplifier should never exceed 1/8th of the nominal impedance of the headphones connected to it), then it becomes obvious that the low-gain setting was tailored for IEM use.
The most sensitive IEMs I have in my possession are FiiO’s hybrid FH19 music-making machines, which deliver an ear-damaging SPL of 109 dB from a single milliwatt of power. Since we’re talking about a SET amplifier, it provides the same power on its 6.35mm (1/4”) and 4-pin XLR jacks. I connected them to the regular 6.35mm jack, turned the volume all the way down, and hit play.
To nobody’s surprise, the FH19s were completely silent, without a trace of noise or hum playing in the background—experiences I’ve already had with the Trafomatic Primavera. Some people still think that tube amplifiers haven’t evolved much, but I’m here to debunk that old preconception. The Envy isn’t only extremely technical-sounding for a tube amp; it’s also noise-free, especially with current production tubes, as some NOS options could still increase the noise output slightly. So far, this is the second tube amplifier that didn’t raise the noise floor with sensitive IEMs, which sadly cannot be said for Cayin’s Soul 170HA, which is sometimes noisy even with desktop dynamic headphones. My usual listening level sits around 8 o’clock on its knob, which is roughly 10% of the volume available. After pausing the music, I could crank the volume to around the 11 o’clock position, at which point the noise floor makes its appearance. However, I would probably damage these IEMs—or worse, my hearing if I pressed play at that volume level.
Considering that I have more than 110 dB of SPL without hearing a trace of distortion or noise, I’m pretty sure most, if not all, IEMs should work just fine on the Envy. After putting the 6SN7 KEN-RAD Black Glass tubes back into their sockets, a slight hiss was present, but please consider their old age, as this particular pair was manufactured in 1947. Ouch!
As you can guess, sensitive desktop headphones performed similarly and even better, as I had extra travel on the volume knob before I could hear traces of noise. The highest sensitivity headphones I own are my co-designed Apos Caspian, which are tailored to be efficient and easy to drive, even from regular sources like smartphones and laptops. With a sensitivity of 115 dB per single mW of power, these reached loud levels in no time, and as much as I tried, I couldn’t detect any traces of noise.

IV. Power Output
The Envy delivers around 8 Watts of power per channel into a 16 Ohm load, regardless of the headphone output, since it’s a SET amplifier. If you didn’t invest in a balanced headphone cable, that won’t be necessary with the Envy, or with any other SET amplifier, as the regular headphone jack is equally powerful.
After toying around for more than two weeks and trying every imaginable headphone pairing, it became clear to me that the low gain was specifically tuned for IEMs and a small portion of extra-sensitive desktop headphones such as Grado and Focal. I used the mid-gain setting 95% of the time, not only because I had more headroom available but also because some headphones sounded a whole lot better. The high gain setting was reserved mostly for the most demanding loads, such as the HiFiMan Susvara OG, Abyss 1266 Phi TC, DCA Stealth, or Expanse, and possibly some 600+ Ohm Beyers that need tons of voltage to be driven.
Team Feliks Audio added significant gain on both the mid and high positions, and most of the time, the volume levels never surpassed the 11 o’clock position. In truth, I never went past the 12 o’clock position, leaving at least 50% of headroom available. Please don’t confuse one Watt coming from a Class-D or Class-AB amplifier with one Watt coming from a transformer-coupled Class-A SET amplifier, as these Watts will feel by orders of magnitude stronger.
My Wavedream Signature DAC pumps around 20 Vpp via XLR out, which is about 7.1 V RMS. This is a much stronger signal compared to your regular 4 V RMS DAC, and this little trick adds extra gain to the Envy, making it even more powerful. It reacted immediately to the higher voltage input, much like the other headphone amplifiers in its class. The only difference is that the Envy never clipped when fed a higher voltage input—a feat that may be less reliable in more affordable amplifiers.
Unsurprisingly, the Envy easily drove the notorious HiFiMan Susvara OG, Susvara Unveiled, HE1000 Unveiled, T+A Solitaire P, and Sennheiser HD800S, all while maintaining plenty of headroom for a loud session. Powerful SET amplifiers excel at juggling with speaker drivers, let alone headphones. It’s like driving at 40 km per hour in a Ferrari SF90 Stradale. You can feel the raw power within, ready to be unleashed upon your headphones. I’m not talking about ear-damaging volumes you’ll reach in no time but rather the remarkable dynamics the Envy is capable of. Both Susvara variants and the Solitaire P spread their wings when fed absurd amounts of power, pushing and pulling their diaphragms like ragdolls.
The HiFiMan Susvara OG was the only headphone from my collection that required high gain; the rest performed just fine in the mid-gain position. The only other thing I will mention is that if you go a little louder than 100 dB with the Susvara OG, some distortion might gently kick in since these typically demand extra power for complete control over their diaphragms. They sounded exceptional at lower volumes, but I don’t recommend throwing disco parties with the Susvara OG on the Envy, as that may stress the amplifier into gentle clipping.
Perhaps the biggest surprise for me wasn’t these unobtainable planar headphones that only a few of us can afford, but the Sennheiser HD800S! I remember trying a loaner HD800S on the Trafomatic HEAD2 that came over for a review and purchasing them the next day due to an exceptional pairing. Honestly, the HD800S are even better on the Envy! The midrange purity adds a kind of magic; the layered bass and the absence of treble grain and aggressiveness make the HD800S feel more like an overcharged HD650 with extra resolution and spaciousness. I sat there mesmerized by the HD800S, which sounded so much better than I remembered. It’s a no-brainer pairing, one of the best I have experienced with the Envy, and it makes me wonder why the HD800S can no longer be spotted at various HiFi shows with the Envy sitting on the same table.

V. Soundstage & Imaging
Ain’t No Sunshine by Tommy Schneider feat. Adrian Stern, Hans Peter Bartsch, and Philippe (available on Qobuz) starts playing, and I’m not sure how, but a second later, a glass of old smoked whiskey appears by my side. It’s 8:00 PM here, and the only thing left to do was recline my chair and feel the soothing vibe of this track. The experience completely relaxed every cell in my body; the T+A Solitaire P almost transformed into my Raidho TD2.2 loudspeakers, and the depth was mesmerizing. The saxophone felt close and personal, then so deep in the mix that it was shocking how much space there was between every note and individual instrument. The interplay between the guitar and saxophone players was a tour de force. For a few seconds, the saxophone player won my admiration and respect, and just a few moments later, the guitarist stole the show for me. However, what stunned me the most was the incredible stereo separation and 3D layering that only well-made tube amplifiers are capable of producing.
Losing Hand by Harry Belafonte from Belafonte Sings the Blues (also found on Qobuz and Tidal) is playing in a music genre I invented a few years ago: gangster blues. Give it a try and focus on the guitar player; if that isn’t gangster blues, then I don’t know what is. The sound is both relaxing and incredibly spacious, yet there is so much atmosphere in the room that you can almost smell the cigars swirling around you when this track fires up those gritty guitar notes. This is yet another track that teleports me roughly 65 years back in time like it’s magic. Recorded, mastered, and mixed more than 60 years ago, this tune is as fresh and alive as ever. Harry’s voice is a bit too polished for the type of music he is trying to sing; nonetheless, he deserves appreciation for the depth and guttural quality he presents here. This track highlights the power of human imagination, with sounds dancing all around you at a considerable distance. Music is not just playing around you; it floats in mid-air, allowing you to grasp musical notes with the power of your imagination.
I remember a couple of folks complaining that we never award 100 points to the gear we review. When it comes to headphone amplifiers, we have had only a single exception to this rule, and that was the white princess—the Trafomatic Primavera in pure white gloss finish, which always sounded like the music was coming from outside the room, mimicking the sound of a near-field stereo setup more than that of a head-fi rig. Considering how much air is moving right now with the Envy doing the heavy lifting, I am compelled to award 100 points to yet another amplifier that has passed through our hands.

VI. Dynamics & Transient Response
You can have all the technicalities and the world’s best measurements, but tell me, would you listen to such devices if they didn’t awaken some sort of experience? How often do you get goosebumps from gear that measures perfectly?
I’ll tell you a funny story. There was a time when I owned the world’s best 10 measured headphone amplifiers around ~2022 and you know what? Those weren’t even close to my top 30 amps that I have ever tested. Sure, you can measure a few things, but there are many other aspects that only our tiny brains can measure, and dynamics are one of those things. But please don’t confuse dynamic range appearing on a screen with dynamics that send goosebumps all over your body, launching you into a five-minute air guitar session.
As I got older, I realized that the act of listening to music is sacred; it’s the only activity that can wire my brain to the universe. Sometimes (but very rarely), I feel connected to something greater than myself, and that only happens when I’m listening to music on a legendary-sounding setup. This is definitely that kind of setup, as once again, I find myself on top of a mountain with sounds pouring down on me like a thunderstorm. Soothing Kind of Love by Lisa Simone (found on Qobuz and Tidal) is a standout track in terms of sheer dynamics. Focus on the bass guitar and the drummer; these two won’t leave you for a second. Good luck looking away or trying to multitask with the Envy pushing and pulling diaphragms on this track. I have a feeling that the guitar player swapped regular copper strings for much thicker strings, as the bass energy oozing from the KEN RAD 6SN7 Black Glass, together with the new-production Western Electric 300B, feels like hearing bass for the first time on the Susvara OG and Unveiled variants. It’s not just the kind of bass you can hear; it’s the kind you can feel with every pore of your skin. It’s thumpy and dare I say, thunderous with the right combination of tubes.
With these particular tubes, I have this weird sensation that the Envy now provides more power, as usually, a lot of power results in a really nice kick in the bass, long sustain, and natural decay. I can’t fault the stock PSVANE tubes; they are still incredibly resolving, noiseless, and technically impressive, but they lack the character I get from the Raytheon or KEN RADs.
In its current configuration, the Envy kicks some serious @ss, even more so than what I have experienced at various HiFi shows. Even the mighty Trafomatic Primavera feels a bit softer sounding by comparison. I should mention that even though the Cayin Soul 170HA is twice as powerful as the Envy, they both sound equally punchy and alive to me, constantly firing machine-gun-like notes with modern tunes. The Envy is ever so slightly faster sounding than the best TOTL tube amps I mentioned above; I can only presume that the solid-state rectification of the Envy makes it a tad faster and punchier than the rest.
Ladies and gentlemen, we have another perfect score, and I take my hat off.

VII. Resolution & Transparency
Considering that I’ve experienced a noiseless performance with three pairs of ultra-sensitive IEMs, a solid foundation has been laid for an extra chapter. A Class-A SET amplifier usually captures your attention with its midrange purity and incredible musical flow, all while eliminating any trace of listening fatigue. The Envy is exactly like that with the right set of tubes; however, since we have high-end transformers on board and point-to-point UPOCC wiring, the Envy is not only lush and inviting but also incredibly resolving. This aspect is what differentiates good tube amps from legendary tube amps. I clearly remember the day the Trafomatic Primavera completed its long-awaited burn-in process and I sat down for a lengthy listen. The awe and shock of hearing everything I thought impossible was so great that I felt compelled to buy it, and that was the best decision I made two years ago. It was the first SET amplifier that sounded as resolving and as clean as a fully discrete (transistor-based) solid-state amplifier while adding an extra sense of realism.
Highly resolving and ultra-transparent tube amplifiers that closely replicate the source material do exist, but they usually demand a substantial financial commitment. The component selection is thus considerably more important in a SET amplifier, especially the quality of the input and output transformers, the chokes, and so on. Feliks Audio didn’t spare a dime on the Envy, and if you opt for the Performance Edition, the final result will be even purer sounding. Starting with the Primavera, I changed my attitude toward tube amplifiers; this is not your regular Little Dot, DarkVoice, or xDuoo, this is high-end material that demands respect and appreciation.
The Envy follows the same winning formula I had already experienced with the Primavera. Small nuances don’t shout at you as they might with solid-state amplifiers that use a fair amount of negative feedback. The Envy presents micro-detail information as if it’s not even trying; everything flows smoothly and gracefully into my eardrums, “effortless” would be the right word, and if I truly listen, I can discern everything, including the strong contour of the notes, if that’s your thing.
The Susvara Unveiled still sounded fantastic, while the T+A Solitaire P and Sennheiser HD800S continued to uncover a wealth of details behind my tracks. I never felt that anything was missing from my music. I’m sure that the downstream equipment and the excellent digital front end were providing significant support, as no matter what music played or which headphones rested on my head, it always sounded impressively clean.
After tube rolling like a madman for a couple of days, it became clear to me that the stock CV181 TII was outperformed by the NOS variants I had on hand. However, what impressed me, even more, was the Ray Tubes 6SN7 RESERVE, which retained all the great traits of the PSVANE but without the nasty ringing in the treble, sounding much more pleasing to my ears while remaining equally transparent. While detail retrieval was impressive from day one on the Envy, what truly stood out for me a couple of days later was transparency. Not only was I able to hear the smallest nuances hidden in the corners of my tracks, but I could also look deeper into them. I could zoom in and out much easier with this amplifier, which isn’t something that happens as often with solid-state amplifiers of all sizes and shapes.
People sometimes associate tube amplifiers with soft, mellow, and sweet-sounding units that roll off frequency extremes and remove information from the lowest and highest octaves. That description fits perfectly with several entry to mid-level tube amps, but the Envy is cut from a different cloth.

VIII. Feliks ENVY Working as a Preamplifier in a Stereo Rig
The importance of having a well-made preamplifier in a two-channel stereo system is well known to me, and up to this point, the most expensive component I have in my HiFi rack is the preamplifier—the Chord Electronics Ultima PRE2 ($20,800). My good friend and fellow reviewer, Catalin, agrees with my assessment. Since he’s driving the same Raidho TD2.2 (yes, we have the same speakers) with 300B SET monoblock amplifiers (Trafomatic GLENN), he decided to go for the full tube treatment and opted for the equally impressive high-gain Trafomatic LARA ($12,000) tube-based preamplifier. We have experienced the immediate change that a good preamp can bring to the table countless times by now, and no! A good preamp isn’t just about controlling the volume; it does so much more.
Having a DAC with an analog or digital volume control doesn’t automatically mean there is a line amplifier circuit somewhere in there. A few exceptions to this rule exist, and sometimes we do indeed test really good DACs with excellent preamp sections (Rockna Wavelight and Lampizator Poseidon come to mind).
There are several reviews online for the Envy, but I’m a bit disappointed that none of these reviewers tested the preamp capabilities of the Envy. Rest assured; you will get your answers today.
In my case, I placed the Envy between my Rockna Wavedream Signature DAC and the Chord Ultima 3 monoblock amplifiers, bypassing the Ultima PRE2 and allowing the Envy to control the volume. The preamp outputs of the Envy bring immense joy to stereo enthusiasts like me, as sometimes solid-state electronics can gain a serious boost in realism and warmth that solid-state designs typically cannot provide so easily. I was quite disappointed not to have preamp outputs on the Trafomatic Primavera, especially since a much more affordable HEAD2 was equipped with them. By comparison, the Cayin Soul 170HA can drive both headphones and loudspeakers, delivering around 18 Watts per channel when used in Ultra-Linear mode. However, 18 Watts isn’t enough to fully control my 86 dB sensitivity speakers, so a well-designed preamp based on 300B and 6SN7 is much more appealing to me.
Since the Raidho TD2.2 represents the pure definition of transparency and detail retrieval, the only tube combination that made sense to use with my setup was the WE 300B along with Ray Tubes RESERVE, which would ideally bring forth the best of both worlds… well, at least in theory.
I wasn’t surprised to find a pitch-black background and noise-free performance, regardless of the volume levels. The noise floor was pitch black, and the sound’s transparency stood out immediately to me, placing the sounds much farther away from the speakers. I didn’t experience two blobs of sound, as I had with my old Chord Ultima PRE3; the sound was by orders of magnitude bigger as if the music wasn’t emanating from my speakers’ woofers, but from a vast blanket of sound, much larger than the 85” TV sitting between the speakers. When I upgraded my former Chord PRE3 to the current PRE2, I did so largely because the sound merged the characteristics of solid-state and tube amplifiers, captivating me greatly. Not only was it incredibly fast, nimble, and technical sounding—controlling everything with an iron grip—but there was finally some lushness and warmth that I had never experienced before with solid-state electronics. The PRE2 won my heart that day, and the only itch I had was to upgrade further.
What’s interesting about the ENVY and the PRE2 is that some of their traits closely match. The bold tonality that brings forth so much oomph and midrange purity is present in both! The “bigger-than-life” sound coming from outside the room is also a shared characteristic. A groovy bass line that shakes the foundations of the building can be found in both setups. I’m sure that the solid-state rectification of the Envy makes it slightly faster and clearer compared to standard tube-rectified 300B amplifiers, and in my case, I didn’t feel that the sound lost any of its charm.
The only two gripes I had with the Envy – only when comparing it with the PRE2 are that the sound wasn’t quite as tightly controlled, especially in the bass region, and I regret that it doesn’t have a remote control, as I needed to manually adjust the volume from time to time. Apart from these issues, with the right set of tubes, the Envy could elevate 99% of the DACs I know today and bring forth a sense of realism, lushness, and effortlessness that you never thought possible with your current setup. The Envy can be easily compared with dedicated preamps, and today’s brief comparison proves it.

Frequency Response
IX. Bass
We have two very different versions of the Envy: one that uses the stock PSVANE CV181 TII and a much more powerful version that swaps them for a pair of KEN RAD 6SN7 Black Glass (or Raytheon, though it’s no longer as intimidating). The PSVANE tubes will impress you more with their linearity and neutrality, never attempting to bite off more than they can chew. With these, the bass is clean, layered, and obedient – maybe a bit polite for my taste. The Raytheons add more muscle to its skinny frame, making the bass sound muscular and, dare I say, punchy. The difference is noticeable immediately; while resolution may decrease, the fun factor doubles with the right music. If you think you’ve discovered a differently sounding Envy, wait until the KEN-RADs make their bombastic entrance, further enhancing the bass presence and calling down the thunder every time a bass note lands on your eardrums. The best part? These tubes are not only incredibly punchy and alive, but they also sound much cleaner than the Raytheons, with a soundstage that feels like it gently expands into your peripheral vision. A flawless-sounding tube combo? You bet! But good luck finding a platinum-matched NOS; these usually fetch around $500-$700 on eBay.
The Envy can be obedient or nasty, polite or intimidating; it really depends on which tube combinations are doing the heavy lifting. Among all the headphone amplifiers I’ve ever experienced, the Envy has only one rival that brings the thunder in a similar fashion—an amplifier that the Envy will be compared to in our next review.
People usually don’t recommend tube amplifiers for bass-heavy drum and bass, aggressive rock, or various genres of underground electronica. I feel a bit guilty, as I too have recommended various solid-state amps that pack a punch, and those are still impressive. However, the Envy is not your usual mellow, slow, and polite-sounding OTL amp; this one is not to be trifled with when dynamics start raining down on you, sounding much livelier by comparison.

X. Midrange
I have a similar story to tell when it comes to the midrange, but this time, it’s not only about the driver tubes but also about the power tubes. The one I hold in high esteem for midrange lushness and warmth is undoubtedly the 6SN7 Sylvania Big Boy. It’s hard to explain in mere words, but it brings forth a sense of lushness that not even the KEN RADs possess. Pair the Sylvania with a set of current production Western Electric 300B tubes, and you’ll get a milk-with-honey presentation—lush, organic, and sweet, in contrast to the dead-neutral representation of the Electro-Harmonix + PSVANE combo. Swap some tubes and find your sweet spot; the Envy will change its character and reveal a different tonality that you thought impossible at first.
The Western Electric power tubes might not have the lushness of the NOS variants, which easily demand the price of a brand-new Envy, but I still find them magical sounding, especially in the midrange region. I wish the Cayin Soul 170HA or the Primavera could provide as much lushness and vividness as the Envy is capable of with the right set of tubes.
My mother was a singer in her youth, and ever since I saw her perform on stage as a child, I have remained fascinated by female vocals, especially sopranos. Caruso by Sarah Àlainn (found on Tidal) unlocked a distant memory that sent shivers down my spine. Words fail to describe the emotions I felt at that exact moment. Her voice was so close to my ear, whispering gently as if telling a midnight story, only to explode a minute later in a powerful way. In just 4 minutes and 10 seconds, this simple yet majestic track awakened every cell in my body. Sarah’s long sustains and high-pitched voice… I was amazed by how deeply her voice was embedded in the mix, taking center stage before my very eyes.

XI. Treble
You won’t be surprised if I told you a similar story about the treble rendition, will you? If you love hearing everything, then nothing does it better than the Ray Tubes 6SN7 RESERVE combined with current production WE 300B tubes. I’ve heard that ELROG’s 300B tubes are even clearer and more extended-sounding. The stock PSVANE tubes are no slouches; I consider them to have excellent extension well above the top octave, with a somewhat hotter tonality, especially during the first hour of use after powering on the amp. If you adore smooth transitions from the upper midrange to the treble region and a gentle roll-off that prevents any listening fatigue from plaguing your sessions, then nothing does it better than some new old stock tubes from the West. If you’re hunting for a great deal, check www.reverb.com; it’s the place where I snagged most of my NOS tubes.
The Envy is again showcasing its chameleon-like characteristics, mimicking the sound of a well-made solid-state amplifier with the stock PSVANE or presenting a much smoother character once you switch to NOS. Among the ones I have, the Sylvania Bad Boy and Raytheon Tall Boy 6SN7 mix milk and honey for a relaxed listen. The interesting part is getting all of this from a single amplifier; it feels like having three alter egos with three very different tonalities residing in the same chassis. How is this even possible? I guess a no-compromise parts selection allows the tubes to show off their true nature, exposing all their strengths and weaknesses, and this is what I like most about it. It’s both ruthless and sweet-sounding, just pick your poison and follow the white rabbit.

XII. Tube Rolling
In Dante Alighieri’s work Inferno, the famous words perfectly describe the tube-rolling potential of the Envy: “Abandon hope all ye who enter here!” Considering that 300B tubes are the most widely acclaimed power tubes and 6SN7 tubes are the most commonly used double triodes, you have a myriad of tube combinations to choose from. Although several tubes will be presented here, this is only a small fraction of what can be swapped with the Envy. Luckily for me and my sanity, the Envy has only four tubes, and believe me, this is going to save you a lot of cash.
A. Driver Tubes
- JJ Electronic 6SN7 (~$50 per matched pair) – Throw them in the trash bin. Simply put, these are the worst 6SN7 variants I have on hand. I’m a bit sad that the Cayin Soul 170HA comes bundled with these, as the sound improves with any other tube you might consider. The sound is too sterile for my taste, and the worst part is that the soundstage feels botched, shrinking on both the X and Y axes. Boo!
- Ray Tubes 6SN6 Select ($149 per matched pair) – A big step up from the JJ’s; everything becomes larger and airier, stereo separation finally becomes a reality, and tons of nuances start emerging from the shadows. These no longer screech with treble-intensive tracks, and their build quality seems fantastic. I expect these to serve me well for at least ~5 years, and you don’t need to invest a small fortune for an extra pair. These are great, but I still don’t hear the magic that the Envy is capable of.
- PSVANE CV181 TII ($200-$220 per matched pair) – Regardless of the edition, the Envy comes bundled with these tubes, and mind you, these are (MUCH) better compared to the stock JJ Electronic 6SN7 I’ve got on the Cayin Soul 170HA that should be banished from existence. I don’t think a cheaper 6SN7 variant exists today, but the CV181 TII is not only four times more expensive, but it’s also considerably more technical sounding. You can hear additional nuances, and micro-details start appearing everywhere in your music. The noise floor is second only to the Ray Tubes Reserve, and I totally understand why the Feliks Audio team went with these. The only aspect I don’t like about the CV181 TII is their overall tonality, which lacks the tube lushness I tend to expect from double triodes, sounding more like a transistor. Nothing wrong with that, but it’s not what I want to escape into when listening to music, and that rarely happens with this set.
- Ray Tubes 6SN6 RESERVE ($480 per matched pair) – A significant step up from the SELECT and a marginal improvement over the PSVANE tubes. They look very similar to the PSVANE, and I have a strange feeling that both of these are made in the same factory (although I can’t check or confirm). Personally, they look a bit nicer than the PSVANE; I like the color scheme and the attention to detail is even better. They sound very similar to the PSVANE, with the exception that I no longer perceive them as clinical sounding. The sound is a bit more relaxed and less aggressive, with some of the tube magic coming through in the background. If you need the most universally appealing, highly resolving, and technical sound at every step, then these are playing a game of eternal solitude. Absolutely stunning from every angle!
- Raytheon 6SN7 Short Boy (New Old Stock, ~$100-150 per matched pair). You can find these everywhere, including on eBay and Reverb.com. The sound is a bit noisier, and the background is no longer pitch black as it is with the RESERVE and CV181 TII, but the sound is much softer toward your ears, and let’s not forget the extra energy that oozes from the bass region. For bass heads out there, this should be your starting point.
- Raytheon 6SN7 Tall Boy (New Old Stock, ~$100-150 per matched pair). Very similar to the Short Boy, except that the sound propagates deeper, providing extra depth and holography, though with slightly less bass impact. Everything else is on the same level as the Short Boy. The sound is always lush, and bombastic in the bass, the treble is calm and relaxed, and the midrange offers a bit more body compared to current production tubes.
- KEN RAD 6SN7 Black Glass (~$500-700 per matched pair). This is Thor’s Thunderclap, Odin’s Wrath, and Zeus’s lightning strike in a vacuum. Seriously though, these will impact your eardrums like nothing else. The bass energy oozing from them is nothing short of spectacular. Can you have too much bass? I think you can with a pair of KEN RADs, just make sure to get the Black Glass version, which has much better tolerance numbers and sounds even clearer than the regular ones. These are also the only NOS tubes I have that challenge the current production tubes in terms of sheer resolution, clarity, and soundstage. They may look nasty, but they sound gorgeous, adding extra oomph not only in the bass but also in the midrange while nicely controlling the treble output. They have one single con: their noise floor is a bit higher than usual, so forget about using IEMs with these, but don’t worry about pairing them with desktop headphones. Unsurprisingly, these are my favorites!
- Sylvania 2 Hole Bad Boy 6SN7 (New Old Stock, ~$150-300 per matched pair). Probably one of the most impressive tubes I’ve tried when it comes to midrange warmth, sweetness, lushness, and a vast, open soundstage. These don’t bring the thunder like the Raytheon or KEN RADs do, but there is still plenty of energy down low. They work best with blues and jazz; the vocals never felt more present in the room, to the point of becoming almost spooky real! Some of my favorite jazz players seem to come back from the grave with these tubes, adding a sense of realism that no other tubes can match. They may not be the perfect NOS for me, but they are perfect for enjoying old smoky jazz and blues with a glass of whiskey on the rocks nearby. Prepare some tissues, as a comedy-drama always unfolds when the music starts playing.

B. Power Tubes
- TJ FullMusic 300B Solid Plate (~$500-800 per matched pair). Since I’ve reviewed the Performance Edition of the Envy, I no longer have the stock Electro-Harmonix Gold 300B, but instead, I have the FullMusic treatment. Don’t confuse these with mesh plate variants, as they have solid plates instead. Interestingly, these sound slightly louder than the Western Electric tubes. The sound is crisp, detailed, and a bit sharp, yet tonally rich and quite seductive. The noise floor is incredibly low, as is typical with most Chinese tubes these days, and overall, I find them very technical sounding without becoming clinical or boring. They seem to be a significant step up in resolution from ordinary JJ Electronic, Sovtek, and Electro-Harmonix tubes. The good news is that I don’t find them overly bright on top, as the Sophia Electric 300B solid plates sounded to me in the past, and I also find them a bit more dynamic compared to the Emission Labs 300B (which I no longer have at my disposal). They represent a substantial improvement over the regular tubes you might find in a guitar store around the corner.
- Western Electric 300B ($1500 per matched pair) – Lush! Rich! Sweet! These sound a bit smoother compared to the FullMusic ones. The midrange stands out from the crowd; it isn’t only denser and fuller-bodied, but additional nuances are brought forward, sounding clearer than ever before. These aren’t just lusher and sweeter than everything else I’ve tried, but they are also more technical and resolving at the same time. The sound seems to expand on all axes, and the sound staging capabilities are gradually improving. This particular tube combo scored maximum points in the soundstage department. The build quality also appears to be considerably higher, and let’s not forget the impressive packaging and 5-year extended warranty! These are handmade in the USA, and you can feel the pride and attention to detail that went into bringing these legendary-sounding tubes back to the market. If you need some of the most euphonic-sounding power tubes, your search ends when shopping for Western Electric tubes.

XIII. Epilogue & Conclusion
This was my first experience with Feliks Audio amplifiers in the comfort of my home, but I can confidently say that it won’t be my last. There’s something about the sound of the Envy that always calls me back. The combination of the 300B and 6SN7 is considered the gold standard among tube aficionados, especially when discussing custom-tailored SET amplifiers biased into full Class A operation. It’s not just its voicing that draws me in or the sound that continually shifts depending on the tube combination; it’s also about the aesthetics and the attention to the smallest details. It’s about the complete package you receive with an amplifier of this caliber. It goes without saying that the Envy is a phenomenal-sounding headphone amplifier and preamplifier.
Sure, it’s not the most powerful beast in the universe, but hey! It still drove a range of high-end headphones while putting a huge grin on my face. It’s not a perfect headamp by any means; such a thing doesn’t exist. I still craved a bit more power and control at higher SPLs with the most demanding Susvara OGs, but the rest? They were effortlessly driven to their fullest potential while delivering the most universally loved tuning and impressive technicalities for a SET amp. It’s more like a hybrid, combining the best traits of SET amplifiers with solid-state designs under one roof.
The custom nature of the ENVY, along with the point-to-point wiring, made it crystal clear and highly resolving and let’s not forget the noiseless performance I experienced with three sets of IEMs at my disposal. A noiseless and distortionless tube amplifier sounds like heresy, but that’s what I received with the ENVY at the helm of my headphone battle station.
It sounded equally impressive as a preamplifier, adding plenty of oomph and energy down low without introducing unwanted resonance, noise, or distortion. The soundscape was something to behold; the sound emanated beyond the walls, delivering a true holographic experience. The only drawbacks I see with this amplifier are the long burn-in periods and the lack of a remote control for use in a stereo setup. I only hope Feliks Audio will sell remote controls as an extra accessory for us stereo enthusiasts, but I’ll leave it here, pitching this idea for the next preamplifier crafted by the three brothers in Poland.
For countless reasons, it didn’t feel like an ordinary headphone amp and preamp combo, which is why Feliks Audio’s team deserves our highest praise and award! Congratulations to the team, and we’re excited about what’s coming next.

Its hefty price tag of €6,999 for the Standard Edition or €7,799 for the Performance Edition may deter some headphiles and stereo enthusiasts, and that’s perfectly fine. It’s not for everybody, only for those who appreciate the care that went into sculpting such a statement piece. It’s for those who demand only the very best and have a sizable headphone collection to juggle. If you take the plunge and have any burning questions, feel free to drop me a line in the comments section below. That’s all for now—Sandu signing off!
PROS:
- A one-of-a-kind unboxing experience
- The most striking-looking headphone amplifier we’ve seen to date
- Outstanding finish and attention to the smallest details
- Rock-solid build quality
- One of the most powerful headphone amplifiers available
- Uses only four tubes (your wallet says thank you)
- Impressive layering and sound staging capabilities with the right set of tubes
- Punchy dynamics are positively vibrant in this one, especially with the KEN RADs doing the heavy lifting
- Zero feedback Single-Ended Triode (SET) and full Class-A design make it incredibly real, pure, and organic-sounding
- Noiseless operation with sensitive IEMs, offering a pitch-black background
- The preamplifier section is equally impressive, adding tons of stereo separation, airiness, and a lifelike tonality
- Sounds effortless on the ear; it won’t cause listening fatigue
- Sounds incredibly technical and clean, rivaling even several fully discrete solid-state amplifiers
- Never rolls off portions of the frequency response
- A chameleon-like sound tuning
CONS:
- Needs extra space around it to dissipate heat efficiently
- Long burn-in times: don’t draw conclusions until you reach 150 hours of use
- Requires about an hour of warm-up to sound its best
- Vacuum tubes have a limited lifespan (~5000 hours)
- Lacks a remote control for use as a preamplifier in a stereo setup
- Pricey
ASSOCIATED EQUIPMENT:
- HiFi Racks: WoodYard Suspended Triple & Baby Modular
- Digital Transport / Roon Server/ Streamer: Rockna Wavedream NET 4 Tb
- Network Switch: Ansuz PowerSwitch D3, Matrix Audio SS-1 PRO
- DACs: Rockna Wavedream Signature XLR
- Preamplifiers: Chord Electronics Ultima PRE2, Feliks ENVY Performance Edition
- Power Amplifiers: Chord Electronics Ultima 3 (X2)
- Headphone Amplifiers: Feliks ENVY Performance Edition, Cayin Soul 170HA, Trafomatic Primavera (sadly, it’s now gone), Enleum AMP-23R, LAiV HP2A, Burson Soloist Voyager
- Loudspeakers: Raidho TD 2.2, Ø Audio FRIGG 02 (on loan)
- Headphones: HiFiMan Susvara Unveiled, Susvara OG, HE1000 Unveiled, T+A Solitaire P, Sennheiser HD800S & Many More
- IEMs: FiiO FH19, FiiO FA19, Westone Mach 80, HiFiMan Svanar
- Interconnects: Crystal Cable Art Series Monet XLR (X2)
- Speaker cables: Crystal Cable Art Series Monet
- Power Cables: Crystal Cable Art Series Monet (X4), Roboli Stars (X2)
- Ethernet Cable: Crystal Cable Art Series Monet
- HDMI Cable (I2S): AudioQuest Dragon
- Balanced Isolation Power Conditioner: KECES IQRP-3600
