Hi everyone! Today, I’ll write about the biggest unknowns of the Hi-Fi world: Preamps! But first, we should learn a thing or two about them. How they work, and if you need one or not. Nowadays, almost nobody discusses them, yet they are found in most audio sources, including DACs, CD players, receivers, turntables, and tape players. Undeniably, dedicated preamps are here for a reason, but what do they do? Can they do their job poorly, or can they elevate your listening experience to the next level? Do you need one if you already have a DAC with a volume control? Great questions! And I’ll try to level all of these question marks.
Today, however, I’ll tell you a story about more than just a discrete, fully symmetrical, fully Class-A biased preamplifier, as this fellow can also power all sorts of headphones (high impedance dynamic cans and planar magnetics as well) and there’s also an equally impressive MC/MM phono stage, rocking a DS-Audio optical input as well, providing the cleanest background and the lowest noise floor of -60 dB instead of -40 dB of conventional cartridges, increasing the dynamic range by 20 dB as a result! Although KECES Audio markets it as an active preamplifier, it’s more like a 3-in-1 unit, and I can’t wait to test all of its features.
Although it looks bold and imposing, things are incredibly simple and straightforward on the inside, as everything works in the analog domain only. As usual, you’ll find MOSFET and Silicon NPN transistors, a fully symmetrical input-to-output circuitry, and a full Class-A bias with zero negative feedback for the purest analog signal. Starting with its modest price tag and finishing with exceptionally low noise that shouldn’t limit dynamics coming from your source, the KECES S4 is already looking impressive on the spec sheet. Working as an active preamplifier, accepting a myriad of impedances when functioning as a phono stage, having a 20 dB of analog gain, a THD of 0.0015% at max power, and 5 pairs of analog inputs, we’re talking about the last preamplifier you will ever need. KECES S4 goes for $3.999 in the USA and for €3.999 here locally. There’s some interesting stuff happening on the inside, which I’ll mention in a minute, but until that happens, let’s have a look at it in the usual fashion.
Design & Build Quality
KECES Audio isn’t new around here. We recently tried their feature-packed and incredibly natural sounding Ebravo streamer powered by the P6 linear power supply. We use their IQRP-3600 balanced power conditioner on a daily basis, and we also tried some of their older devices that are no longer in production.
With every generation, the sound got more refined like an old bottle of wine, yet their brand identity, fit, and finish remained intact. Their newest series has undergone several changes compared to their older units. The first thing you’ll notice is a thick CNC-machined case that will shield it against wireless interference. The metalwork is flawless, and the unit looks like a serious piece of engineering.
The S4 borrows the same design cues from their newest devices, having a similar height and width with the S3 DAC and IQRP-800 power conditioner, and if you stack the S4 with its external power supply, then these will have similar dimensions with their S300+ power amplifier. No matter from what angle you’re looking at, S4 screams KECES Audio from afar thanks to smooth lines, thick metal plates, and bold looks, and you can’t remain unimpressed with its no-strings-attached minimalist look, especially after dimming its display.
Its metal feet are of high quality that will nullify nasty micro-vibrations, thanks to rubber absorption pads. Its front plate is quite thick, and overall, it feels rock-solid and well put together. All of my testing took place in the living room, where a 4-antenna wireless repeater is located, including two streamers. Luckily, the S4 didn’t pick any of that noise, thanks to its impenetrable Zumwalt-class casework.
On its front panel, I’m greeted with an overly simplified display that shows only the volume level, and if the blue LEDs are bothering you in the dark, you can disable them completely. All of their units have a back anodized coating, and I wish they would consider making silver anodized finishes in the future, as I like them a bit more.
Biased into full Class-A operation, the S4 constantly consumes 90W, and while heat dissipation isn’t a big concern thanks to well-ventilated cases and massive heatsinks, it will still need proper spacing and a well-ventilated area for a long service life. After about 8 hours of non-stop music playback, I’ve got ~60 degrees Celsius on S4’s top plate with a Bosch thermo-detector and I don’t recommend putting anything on top of it.
So far, KECES 4 is one of the biggest preamplifiers I’ve tested around here, but it isn’t uncomfortably large or heavy. At about ~8 kg or ~17.7 lbs, it can still be part of an elegant-looking stereo setup. Its dimmed LEDs draw little to no attention, blending nicely in the living room and leading to a high WAF. All in all, it feels like a rock-solid device that should withstand the test of time.
Controls & I/O
On its front plate, you’ll find a 4-pin XLR headphone jack and a mechanical switch that lets you select headphone amplifier or preamp operation. On the right, two buttons let you mute the unit or dim the display above, and the volume wheel on the far right also acts as an On/Off button when long pressed. The volume control is based on high-performance analog relays, and you can hear them clicking when adjusting the volume, offering 128 steps – enough for precise volume control.
Flip it around, and you’ll be surprised by the number of analog inputs and outputs. As mentioned previously, it can act as an MM/MC phono stage, and the 6 switches in its close vicinity let you adjust the loading impedance. The DS optical input comes next, and there’s a regular RCA input (line level) as well. Two pairs of XLR inputs are also present, including two pairs of RCA outputs and a single pair of XLR outputs. The 4-pin XLR jack on the far right lets you connect the unit to the power supply via a 4-pin XLR cable. A mini-to-mini trigger cable is also supplied, and it’s mandatory to be inserted, otherwise, the main unit won’t power on.
Under the Hood of KECES S4
The important thing to know is that we are dealing with a fully symmetrical, quad-mono, discrete, pure Class-A preamplifier and headphone amplifier that doesn’t use negative feedback. Or in simple terms – a pure analog preamp and headphone amp that never uses negative feedback to deal with the noise.
The volume is controlled by 48 analog relays that provide exactly 128 steps of volume, and this is also an MC/MM phono stage that supports DS Audio’s optical input (via RCA connectors). It’s a 3-in-1 unit at the end of the day, always working in the analog domain.
Having a peek inside the S4, you should know that two PCBs have been sandwiched together, and you can see only a single PCB from this angle. The preamp stage/headphone amplifier circuit can be seen on the right side of the PCB. There are two modules on top and two underneath that form a fully symmetrical (4-way) circuit. Everything seems to be crafted from discrete components only; not a single op-amp can be spotted.
The input stage seems populated (the lower-left part), and on top of it, you can see the R2R volume control. I counted 24 relays on top and 24 below, so 48 relays in total that provide 128 steps of volume. This is certainly an overkill R2R volume control, but it was mandatory for precise control even at the lowest volumes. The volume goes up logarithmically, which will offer a more precise control at lower volumes. A great idea considering its higher gain than usual (20 dB).
Two massive heatsinks are cooling down four MOSFETs and four Silicon NPN Power Transistors, again arranged in a fully symmetrical configuration that consume around 90 Watts and will dissipate most of the heat within the unit. I measured 65 degrees Celsius on the power transistors and around ~60 degrees on the top cover, which are safe temperatures, but I still don’t recommend putting anything on top of the main unit. You can, however, stack the S4 and the power supply, but please make sure to put the S4 unit on top for better heat dissipation.
I removed the top screws of the power supply and sure enough, KECES didn’t spare a dime on this one, crafting a slightly overkill filtering and voltage regulation stage, not to mention the massive transformers (an EL-Core and a toroid) doing the heavy lifting. Two massive 15.000 uF Rubycon capacitors will be filtering the noise, and 3 voltage regulators bolted to a big heatsink will provide clean power to the rest of its circuitry. The power supply is a bit heavier than the main unit, even if it doesn’t look as populated.
Test Equipment
My source was a Rockna Wavedream NET 4TB working as a Roon server, but also as an offline music server where 3TB of space has already been filled with DSD and DXD (Hi-Res PCM) material, passing the data to a Rockna Reference Signature DAC. Chord Ultima PRE2 was replaced by the KECES S4 that in turn controlled with an iron two two mean sounding Chord Ultima 3 monoblock amplifiers that drove a pair of Raidho TD 2.2 loudspeakers, playing tunes for more than a week before dropping my final evaluation.
All cabling used was of Crystal Cable Monet breed (power, interconnect, Ethernet, and speaker cables). Everything was also powered by a KECES IQRP-3600 balanced power conditioner.
Alrighty, folks, I’m ready for some well-deserved music, so let’s hit some eardrums!
Sound Performance
I. What is a Preamp, and do you need one?
A preamp is a preamplifier designed to amplify the weaker analog signal coming from your source by making it louder – by raising the voltage, preparing it for the next stage – for the power amplifier that follows. Preamplifiers are designed to accept a wide range of impedance, but they will always output a low impedance in order to fully preserve the dynamic range of the source. Power amplifiers don’t like high-impedance signals coming into them, as they will need to work harder to achieve a similar SPL, thus increasing their THD.
A preamplifier can start its life as a simple volume control for your analog or digital source, usually, that’s called a passive preamplifier. Older preamplifiers are also somewhat more interesting versus the newer ones, as they usually have tone controls (bass, midrange, and treble controls), low-pass filters so you could integrate a sub-woofer, even high-pass filters, and many other functions like muting, dimming, stereo to mono conversion, so on and so forth. The more features a preamplifier has, the longer the signal path will be, resulting in a less clean, less transparent signal. Hence, modern preamps no longer have any of that. You should also know that the companies behind their preamps might have different philosophies. One might want to color the sound with the help of vacuum tubes, while others won’t add anything and leave it as clean as possible. I have been using such a preamp for the last year or so, and it’s called Chord Electronics Ultima PRE2. Unfortunately, it’s not for everyone; it’s on the costlier side, and recommending audio gear that only rock stars can afford it’s not something I do regularly.
Before I tell you how the S4 performs in my stereo system, you should understand that I’m listening to my whole stereo setup and not only to the preamplifier itself. The Rockna duo does the heavy lifting, the signal is then pre-amplified by the KECES S4, and then two mean sounding Chord Ultima 3 monoblocks are energizing the Raidho TD 2.2, which I know very well.
The most important thing to know is that the KECES S4 will behave differently with different types of DACs. Those outputting a lower voltage compared to the industry standard 2V via RCA and 4V via XLR and having a higher impedance will benefit a lot more with a unit like this. A small number of D/A converters already have dedicated preamp stages – the Matrix Audio Element X, the Gold Note DS-10 Plus, the EverSolo DMP-A8 and A10, and the Rockna Wavelight. Naturally, such units won’t benefit as much with a dedicated preamp. Most of the sub-$ 3000 digital sources you see today use a simplified digital attenuation circuit to control their volume. However, in practice, a design like that hurts dynamic range, lowering the resolution when touching their volume control, and again, such units would greatly benefit from an active preamp.
II. Sound Impressions
It seems that most DAC makers chose not to include an active preamp stage in their devices, and I don’t blame them for that. It keeps production costs low, and not every single individual needs such a feature. People usually use integrated amplifiers in their living rooms, and of course, headphone afficionados would never use such a feature. Just look around; most R2R ladder DACs below the $7000 mark don’t offer preamp capabilities, not even the top dogs of Denafrips, Musician, Audio-GD, and Holo Audio.
I love my Rockna Reference Signature DAC to pieces. It’s the most feature-packed unit I have tested so far, rocking not just an outstanding DAC section but an equally impressive streamer, Roon endpoint, and upsampler. However, even at $26.000, it doesn’t offer an active preamp stage, instead relying on digital volume attenuation. The Chord Ultima PRE2 thus adds a tremendous value, not only tightly controlling the volume of the monoblocks that follow, but by also adding qualities of its own, like decompressing the sound, enhancing the focus and transparency, further expanding the scale of the music, smoothing out the rough edges and making everything much easier on the ear. I must confess that after the Reference Signature, the second biggest impact I’ve heard in my stereo was the moment when I added an active preamplifier. I no longer use the Ultima PRE3, but I still remember the shock I had when an active preamp stage was finally controlling my former Benchmark AHB2 monoblocks.
I don’t understand how the same signal coming from my DAC can further increase the width and sound’s depth by adding an extra active component like a preamp, and I couldn’t comprehend how the bass was no longer shaking the foundation of the building while remaining as strong and impactful. Chord’s Ultima PRE2 needs to be heard to be believed, as it brought an ultimate control that wasn’t present before; the boominess went away, decompressing every track and adding lots of air all around. What was limited became limitless, be it the depth, height, or width of the stage. The sounds were no longer limited by the room’s size…an old audiophile cliché, but I kid you not, this is exactly what happened. Remaining deep reaching and punchy to the core, the bass note became clearer and way more controlled than before.
My wallet was giving me an ugly face, but I couldn’t go back to the old sound that was clean but sterile, too close and personal, limited in size and enjoyment.
After swapping it with the KECES S4, it was obvious that besides being resolving and transparent to its core, it added some organic matter into my room, a bit more than the Chord, while remaining punchy and impactful in the lowest octaves. The S4, like the PRE2 before it, added a bit of soul and warmth to my tunes. A bit of sweetness could also be felt in the air, as if I had switched from a mediocre Class-D amplifier to a fully discrete Class-A monster. Sometimes, it even feels like someone swapped the solid-state output stage of my DAC with a couple of tubes, without telling me about it, as the sound became easier on the ear, showing off the beauty within rather than enhancing the contour of the notes. With the KECES S4 in place, the music became weighty, the bass and midrange were now playful, more so than the treble, and it scared away all of the listening fatigue with its smooth and liquid character.
Considering we are dealing with a discrete circuitry and Class-A working principle that doesn’t apply nasty tricks such as negative feedback, it shouldn’t be a surprise getting lots of meat on the bone in return, lots of texture, weight, and a higher sound density. The S4 offers a palpable and cavernous type of sound, filling the gaps in the room and bringing some effortlessness along the way.
My Raidho TD 2.2 are uber transparent, these are detail-oriented speakers that won’t hide anything from you. Like it or not, the TD2.2 are my truth bringers, and I love them for that. Thanks to them, my job has become so much easier.
The only problem? All of the cons of downstream equipment become so apparent that these are constantly asking for upgrades, hence swapping the PRE3 with the PRE2, the Ultima 5 power with Ultima 3 monos, and the Wavedream Signature DAC with the Reference Signature DAC, all happening in less than a year. Nuts! The interesting part is that the S4 didn’t alter the sound’s balance versus my Chord Ultima PRE2, as I believe these two sound incredibly similar, with the exception that I can select several gain settings on the PRE2, as opposed to having a single gain position on the S4.
III. Noise Floor
The noise is a scary mythical creature, audiophiles are trembling in fear after hearing its name. Only the bravest souls are going to great lengths, fighting it fiercely until banishing it for good. It can start as a simple ground loop, sometimes as a faulty cable or questionable cable shielding, sometimes it’s the current that flows through AC lines, but sometimes it’s much worse than that, as it comes straight from your electronics!
We’re testing all sorts of equipment, starting with affordable Hi-Fi and finishing with high-end stuff. We had several unpleasant experiences along the way, but most of them came from entry to mid-level amps that weren’t meant to be used with revealing loudspeakers such as TD 2.2. The loudest noise floor we experienced so far came from affordable Class-D integrated amplifiers, hearing it even from ~2 meters away with music on pause.
The tantalum diamond drivers and the weightless ribbon tweeters of the Raidho TD 2.2 are extremely sensitive to noise coming from downstream equipment. Even with music on pause, they could sniff all the bad stuff. The Rockna DAC is a noiseless-sounding unit, and Chord’s Ultima line lives by the same principles, even powered by switching mode power supplies. Ultima PRE2 offers a gain factor of one (unity gain) and many other gain settings, and usually, you can’t get a clearer-sounding preamp than this. After swapping it with the S4, the noise floor didn’t go up with or without music playing. I even approached the ribbon tweeters, but I always got the sound of silence.
There’s an ultimate noise sniffer test fit for the S4: connecting all sorts of headphones to its 4-pin XLR headphone jack. I used several desktop headphones ranging from dynamic to planars, and to nobody’s surprise, the noise floor was always in check. The noise floor didn’t rise with the music on pause, and that’s as good as it gets in terms of noise suppression.
IV. Resolution & Transparency
The biggest fear I had while exchanging the PRE2 with the S4 was that the super-resolving sound of my system would be no more and some tiny details would be lost in transit. I swapped the PRE2 with the S4, and my heart started beating faster. A preamplifier might improve several things, but it can also add noise and distortion to the mix, and that’s the last thing you want in your (revealing) system. My face brightened immediately…as everything appeared in a crystal-clear manner, low-intensity notes were still dancing around my listening spot, and all the imperfections I knew on older recordings were still in place. A whisky on the rocks, a few albums later, and the S4 still appeared resolving and squeaky clean, but without becoming clinical or worse, limiting dynamics in the process.
That hazy, unpolished, and raw delivery of pre-70-ties jazz and blues was again present in my room, and I’m kind of happy for that. When I went lower on the volume, all the smallest nuances didn’t hide in the shadows; they were still lingering around and whispering in a language that we know so well. I was surprised by how balanced my setup sounded in the evening at a lower SPL. All the fullness and midrange density that the KECES is capable of wasn’t toned down. The warmth and naturalness coming out of these speakers was going through the roof, and I didn’t need to bring the volume to 90 dB or higher to feel the power of the sound.
Knowing that the TD2.2 sounded as smooth and relaxing as they did with my own preamplifier with the right selection of music made me realize how much more interesting the S4 becomes, especially considering the extra features it provides and its lower price point.
On the surface, I Wish by Marcin and Hayato Sumino (found on Qobuz and Tidal) seems like an ordinary acoustic track, where two maestros try to show off their skills. One plays the classic guitar like it’s a 3-in-1 instrument, using it as a drum, guitar, and violin, while Hayato plays with piano pedals like he’s in a Formula 1 car on the race track. The play is short but so imaginative and unusual. It’s exactly the kind of music you would expect from Marcin and Hayato: short, playful, powerful, and incredibly dynamic, like a rush of caffeine in the morning. The best part is that no matter how often the tempo was changing, how smooth or powerful the beats were, the S4 was always in control of every upbeat and downtempo, sounding alive and punchy when needed and relaxing on other occasions. My feet started moving on their own, so I put this track on repeat several times, and I hope you’ll enjoy this tune as much as I did. Don’t forget that you can always follow these incredibly talented individuals on Qobuz, Tidal, or many other streaming platforms for more uplifting music like this.
V. Dynamics & Transients
It’s no secret anymore that I love my beats alive and impactful. I love a deeper rumble down low; I love strong kicks into the chest. I love experiencing butterflies in my stomach, toe-tapping, and even smiling when music speaks to me. This is who I am, and I won’t hide around the bush. If the planets are perfectly aligned, then I’ll get an emotional connection with my tunes.
I have tried several preamps over the years and even more power amplifiers, but finding the perfect trio that would bring an amazing impact down low without leaving residual energy in the bass and treble was (much) harder than I anticipated. My former Benchmark AHB2s were sometimes boomy to the point of shaking the walls of my listening room. I tried everything to lower the echo and reverb. I’ve added two Artnovion bass traps (I still use them today), I tried diffusion and absorption panels of different shapes and sizes, and all of them brought forward a nicer control of the sound and a lower reverb. However, nothing added as much grip and control like the Ultima PRE2.
The bass excess vanished in mere seconds. The sound was exactly as punchy and alive, but the walls of this building were no longer dancing to the rhythm of the music. My speakers weren’t the problem; the preamp and my power amps were the problem. I know that I won’t change my Ultima 3 monos in the distant future, but I’m probably going to play around with a few amplifiers. At the end of the day, where’s the fun of listening to the same setup over and over again?
The KECES S4 is undeniably an impressive-sounding preamplifier if you care about dynamics! It never messes with negative feedback, it’s biased into full Class-A operation, and it rocks a discrete output stage. And if you know a thing or two about electronics, then you already know that a higher tier for solid-state preamps doesn’t exist. The more I used the S4 in my system, the more I realized that the sound is never pressing on the brakes. On the contrary, it takes flight!
With it, the music becomes real, with a clear and defined bass delivery. Dwindling layers of sound strengthened their numbers, with lots of sounds floating all around. If you admire high-quality bass, with layers coming slowly one after another, then I don’t think you will remain unimpressed, to say the least. I’ll go as far and mention that I like its sound a bit more compared to my former Chord Ultima PRE3 ($8.900) that added a bit of edginess to the sound and a less impressive grip, and it seems punchier, denser and groovier sounding than the LAiV Harmony HP2A ($2.700).
VI. Headphone Amplifier Section
The most interesting test I left for last. You see, headphone listening is as important as my stereo addiction. I still use a wall of headphones, and when my tribe is going to sleep, I tend to use headphones (usually closed-back) for about an hour before going to sleep. Some albums are also not suited to be enjoyed with the family, and that’s when I usually tend to use open-back headphones during the day.
My current favorites are T+A Solitaire P and the HiFiMan Susvara Unveiled. Both are extremely resolving, clean, yet dynamic and lively sounding. However, with the right electronics, the Solitaire P is a bit more dynamic sounding in the bass, and the Susvara Unveiled is a bit more emotional in the midrange. KECES does not specify on its website or in the user manual the power output of its headphone amplifier section. It’s like they don’t want to flaunt it as an amazing feature.
This feature, however, felt like a golden treasure to me, not because it was capable of driving these nasty sounding headphones but because it sounded like an S-tier amplifier – getting refined and incredibly dynamic! The 8 power transistors you see bolted to massive heatsinks are used to drive headphones. These are biased into Class-A operation, and these are drawing power from the big power supply sitting underneath the S4. This isn’t an overlooked feature! Oh no, this is a proper headphone amplifier crafted at a high level. How high? It’s not as powerful as the LAiV HP2A, but it’s as punchy and dynamic. It’s not leaving as much headroom on tap as the Enleum AMP-23R, but it’s as organic sounding. It’s not as powerful as the Burson Soloist Voyager, but it’s exactly as speedy. And it’s not as feature-packed as the Ferrum OOR driven by the HYPSOS power supply, but it’s as meaty and textured. And let’s not forget its sound staging abilities that are close to a dual Flux Lab Acoustics MENTOR stack.
I couldn’t believe what I heard, but I started afresh again the next morning, and sure enough, the sound was again effortless, powerful, dynamic, airy, and oh so organic and natural. But please don’t take my words for granted. If you have the opportunity, do try the S4 not only as a preamp but also as a dedicated headphone amplifier.
My Rockna Reference Signature outputs 7V via XLR, and I’m pretty sure it added a helping hand, gently raising the gain level and the headroom. With regular planar headphones such as Meze Elite, Kennertorn Rognir, and Erzetich Phobos, I never went higher than 70 out of 128 steps available. With much more difficult loads, such as T+A Solitaire P, I needed to crank the volume to around 85, and it was around ~95 with the Susvara Unveiled. I still had plenty of headroom remaining on tap, and reaching maximum volume would be impossible, especially if you want to save your hearing and your headphones from permanent damage.
Nonetheless, I remained impressed by the S4, and it could be easily compared with the best solid-state headphone amps I have tested so far.
VII. Quirks
The only two cons I found with the S4 is that only a single gain of 20 dB is offered when working as a standalone preamp or headamp. I would love to have a unity gain option (1X gain) or even 0.5X gain so I could push my monoblocks to their upper limits. The Ultima 3 mono can push up to 1000 Watts per channel in 4 Ohms and 480 Watts per channel in 8 Ohms, add 20 dB of analog gain and even with low sensitivity loudspeakers such as TD 2.2, you’ll hardly go past 35 volume level, out of 128 steps available. But I get it, the S4 was mainly made to work with their S300+ power amplifier that can also function as a mono amplifier if you add another unit. This small quirk could be a plus for you, especially if you use a SET amp that will provide you 15 to maximum 25 Watts per channel at best. The extra gain can be beneficial with lower powered amps, and you’ll get a higher headroom in no time.
The second downside (it’s more like nitpicking) is that Class-A preamps usually generate a good deal of heat, and the S4 is no different. 60 degrees Celsius on the top plate, just on top the power transistors, is not an alarming temperature, but it’s higher compared to the 45-degree temperature of my own preamp. This higher-than-usual temperature won’t impact the component’s lifespan since only a very small area reaches this temperature, but you still need to make sure to have some proper spacing all around it. Better yet, you can further elevate the S4 from its power supply by adding external footers that will lower the working temperature of the S4 by several degrees.
My Conclusion
Now you know what a preamplifier does and if you need one or not. I know a few people who deliberately use tube preamplifiers, inducing extra doses of warmth, liquidity, and sweeter harmonics in their setups. Shockingly, the KECES S4 is quite similar in this regard, albeit sounding a tad clearer and tighter. Its tonality is on the organic side of things. It pushes dynamics to the fun side, yet it’s still transparent and faithful to the source, be it an analog or digital one.
Very few manufacturers put powerful output stages or dedicated line-amplifier circuits in their DACs, and with such units, a preamplifier would seriously improve the performance of your setup. Considering that it stood shoulder-to-shoulder with a much pricier preamplifier (Ultima PRE2), I find it accessible for what it did in my stereo and I’m curious how it would perform in yours.
Please don’t get sad that I was unable to test its DS Audio optical input or the MC/MM phono stage as it uses the same analog circuit to amplify the voltage and control the volume, and in the end, you’ll get similar results. The preamp stage had the same sound characteristics as the headphone amplifier section, and I won’t be surprised if the phono stage sounds as meaty, lively, yet airy and organic.
After testing more than ten active preamplifiers, I can name maybe three units that impressed me deeply, and the S4 is part of this trio. Yes, it’s on the costlier side of things, currently going for $3.999 in the USA and for €3.999 here locally, but at the same time, there wasn’t a thing I disliked about its sound and let’s not forget this is not just a mere active preamplifier, but a fully-fledged headphone amplifier capable of driving difficult loads and a powerful phono stage is also in there.
My second Highly Impressive award for 2025 goes to KECES S4 for excellent sonics at a price that makes sense, and I hope I’ll have the chance to try out their S300+ power amplifier in the near future.
The KECES S4 was graciously provided by KECES Audio. If you wish to inquire about an audition, please contact your local distributor. A full list of distributors can be found right here.
If you take the plunge and still have some burning questions, feel free to drop me a line in the comments section below. That’s all for now – Sandu signing off!
PROS:
- Great Fit & Finish
- Minimalist look with a simple industrial design
- Metallic remote control
- Excellent connectivity and I/O options
- Impressive component selection and power supply implementation down to the smallest details
- Fully discrete, fully balanced, Class-A biased with zero negative feedback – it doesn’t get any better than this
- A 4-in-1 device with none of the compromises
- The headphone amplifier section turned out to be a pleasant surprise, driving even some of the hardest loads out there with plenty of headroom remaining on tap
- Clean and resolving sounding, without becoming clinical or boring
- Dynamic and lively sounding, it’s undeniably a fun sounding unit
- Great layering and stereo separation
- Noiseless as a preamp or headamp
- Although pricey, I still consider it a bargain
CONS:
- A fixed gain of 20 dB is provided as a preamp and headamp, it would be nice to have additional gain settings
- The top plate gets hot after several hours of use, and it needs proper ventilation all around
ASSOCIATED EQUIPMENT:
- Digital Transport / Roon Server: Rockna Wavedream NET 4 Tb, EverSolo DMP-A10
- Network Switch: Ansuz PowerSwitch D3
- DACs: Rockna Wavedream Reference Signature
- Headphone Amplifiers: KECES S4, Cayin Soul 170HA, Feliks Envy Performance Edition
- Preamplifier: KECES S4, Chord Electronics Ultima PRE2
- Power Amplifiers: Chord Electronics Ultima 3 (X2)
- Full-sized headphones: HiFiMan Susvara Unveiled, HE1000 Unveiled, T+A Solitaire P, Kennerton Rognir, Sennheiser HD800S & many others
- Loudspeakers: Raidho TD 2.2
- Interconnects: Crystal Cable Monet XLR (X2)
- Speaker cables: Crystal Cable Monet 2.5m
- Power Cables: Crystal Cable Monet 1.5m (X4), Neotech NEP-1001 (X2)
- Ethernet Cable: Crystal Cable Monet
- HDMI Cable: AudioQuest Dragon
- Balanced Isolation Power Conditioner: KECES IQRP-3600
- Audio Racks: Woodyard Suspended Triple & Baby Modular
