AmplifiersHeadphone Amps
Overall Score: 90/100

SMSL SH-9 THX-888 Headphone Amp Review

My Video Review:

Ever since publishing my Benchmark HPA4 review last year, I couldn’t sleep at night because of the huge differences between it and the second-best headphone amplifier I’ve tried before it. One month later, I smashed my piggie banks and killed my wallet for good, by purchasing an HPA4. That was probably the best decision I’ve made last year, because I was squeezing the best my headphones could possibly offer, but also because reviewing DACs and headphone amplifiers become a whole lot easier for me. I see it not only as an ultimate headphone amplifier and preamplifier, but also as a tool that helps me tremendously with headphone, amplifier and DAC comparisons.

Time passed and plenty of competitors released their own headphone amps with THX-AAA modules that were firing alarming shots in the direction of HPA4. I’ve listened to the Drop THX-789 multiple times, it was included in several reviews and comparisons of mine, here is an in-depth look of three THX amplifiers that I’ve compared. SMSL released their first THX-AAA based headphone amp soon called SP200 that I’ve also reviewed here and to my surprise in few key areas as slam and engagement factor, it was outperforming the Drop-789 by a long shot. Its low price point did shake the market pretty badly, that Drop decided to lower its price point from $399 to $299 so they could compete again.

This year, SMSL is landing another critical hit to the Drop-789 by releasing not one, but two THX based headphone amplifiers: The SH-9 that I will be testing today and the quad-mono, true balanced SP400.

Besides the flagship THX-AAA-888 modules, both devices have a lot of things in common with my beloved Benchmark HPA4, but more about that very soon.

Unboxing Experience

It is already a standard seeing everything double boxed and filling the product box with lots of foam for a better protection during shipping. SH-9 is quite small looking and lightweight, I’m pretty sure it doesn’t have a linear toroidal transformer inside. Besides the unit itself, you will find a power cord and a big surprise: a remote control! Now we’re talking, finally some competition to the HPA4! There is also a warranty card and a very detailed user manual in English that will guide you through its user menu, do check it out, it is very informative.

This is pretty much the same package and the same box that is coming with their SU-9 DAC and as you can imagine, they were made to work as a team. If you already own the SU-9, then SH-9 seems like your next logical step for a complete headphone setup. Just make sure to put SH-9 on top, as it dissipates a lot more heat.

Design & Build Quality

Ever since owning the Benchmark HPA4, it became so easy knowing the exact volume level, the exact selected input, it’s so easy playing with its settings by using its touch screen or remote control. Ever since, I want those features in all headphone amplifiers I’m testing, it is a big quality of life improvement. I have memorized the exact volume position for all my favorite headphones, I know that with Audeze LCD-4, I’m at -25dB and with Hifiman Susvara I’m at -2dB. Without a screen, I need a lot more time adjusting the volume until I reach my desired 85 dB listening level. I’m so glad SMSL put a small LCD screen in here and ditched all those 3 switches, it is a lot cleaner looking now and more elegant than ever. That colorful LCD screen and the included remote control is a direct shot in the face of HPA4. Slowly but steadily some of the best features of HPA4 can be now seen in much lower priced amplifiers.

As for the unit itself, it looks like a matte-black metal brick, that is milled on a CNC machine with just two panels attached on top and under the unit. Its body has a thickness of about 3.5 mm, so wireless interference shouldn’t be a problem at all. The front panel houses a glass sheet with an LCD screen behind it. The volume knob is a huge upgrade to the one found on SP200. It doesn’t wobble at all, it is a stepped volume knob with exactly 99 steps. The best part of it? It’s using a ladder of high-performance analog relays to control its volume. Yes, that is a high-end relay controlled stepped volume attenuator, exactly what I have in the Benchmark HPA4 and exactly what Flux Labs Acoustics put in their FA-10 and FA-12 amplifiers. There are 3 rubber feet underneath the unit and if you have heavier power cords as I do, it might drag it down or lean it to the right. You can separately buy few additional rubber feet, detach the one in the middle and put two in the corners so it will not wobble on your table. I find the build quality really nice and I have close to zero complaints. SMSL moved most of its screws on the back and under the unit, so it would look much cleaner. Underneath the unit, I am spotting an unknown 7-pin connector, exactly the same one I’ve seen on their SU-9 DAC. I’m not sure what it is, maybe for a docking station of some sort, or maybe it helps in servicing their units – that is a strong possibility. Everything else looks really nice, everything is secured tightly, nothing is wobbling with 4 feet instead of 3, it looks clean and minimalist, with a very high WAF factor.

SMSL is offering it only in matte-black and at just 790 grams or 1.75 pounds, it feels like an ultra-compact headphone amplifier, with a lot of power under its hood. It’s so small, that you could easily place it in very tight spaces or in a killer headphone setup – it’s really versatile.

Controls & I/O

SH-9 has a clean looking front panel, with just a volume knob that works as a menu navigator, plus an LCD screen in the middle makes it quite a looker. LCD screen is moderately big at 1.9”, but thanks to its bigger lettering you can clearly see the volume level, the selected input and gain position.

On the back you can spot two analog inputs, a balanced XLR and a single ended RCA one and a universal 100 V to 240 V AC inlet.

Menu Options

All the features of SH-9 can be controlled via its remote control or via its volume knob that doubles as a joystick for its menu. In the stand-by mode a single press on the knob will power it on and another press will enter its menu where you can select:

  • Input – Balanced (XLR) or Unbalanced (RCA) – very straightforward
  • Gain: Low (0 dB – best setting for IEMs or sensitive headphones) or High (+10 dB – for your power-hungry headphones)
  • Volume Mode: Enable or Disable. When its enabled, it will reduce the frequency of relay operation, thus increasing the service life of those relays. If you disable this feature, you will hear clicks on every step.
  • Brightness – 6 positions, lowest one is almost dimming it completely
  • Version – will show your Hardware and Software version (for now it is at version 1.0)

Under the hood of SH-9

So far, SH-9 is the third THX-AAA-888 dual mono equipped headphone amplifier on the market. These are the highest performing modules, that should be used only in no-compromise amplifiers of all sorts.

If you never heard about them, THX AAA modules are reducing harmonic, intermodulation and crossover distortion by 20 to 40 dB offering a true to life, realistic and a fatigue-free listening experience. It accomplishes that by using a patented feed-forward topology to null conventional distortion and noise levels, resulting in the world’s most linear amplifier. THX AAA allows the amplifier to reach its maximum power without any kind of distortion that would normally appear in traditional amplifiers.

SH-9 will deliver up to 6W of power into 16 ohms or 3W in 32 ohm loads on both ¼” and 4-pin XLR outputs, it doesn’t really matter if you have a balanced headphone cable or not, as it will deliver its full power on both headphone jacks. With all those impressive numbers it should drive even the most demanding headphones as high impedance dynamics or current-driver planar-magnetics, l will of course test both instances.

It has an output impedance close to zero ohms, so damping factor should not be affected at all and at only 1.9 micro volts of noise A-weighted, it should pair nicely even with ultra-sensitive IEMs. What I really like about THX AAA amps is that they have their noise floor undetected at any volume levels, but will see about that very soon.

All that power will mean nothing if there isn’t a wide bandwidth and speed to deliver all that instantly to your headphone. The bandwidth of SH-9 extends from 0.1 Hz to over 500 kHz! Meaning that SH-9 will deliver an instant amplitude and should have a perfect phase accuracy over the entire audio bandwidth. Time to upgrade my hearing apparatus with bat ears…

Since a very low noise amplifier will need an uber-low noise volume pot to preserve all the dynamic range and all the bits of the digital source, SMSL developed an advanced relay-controlled volume pot. In short, it all was possible by using several 256-step relay-controlled attenuators. HPA4 is also using a relay-controlled volume pot, but instead of 9 relays that are found on SMSL SH-9, HPA4 is using 24 of them to offer a state-of-the-art precision. Nonetheless, a high-end relay-controlled volume pot in a device that costs only $290 / €320 is something I never thought was possible, but I’m glad we are living in times like these. Seriously, there is never been a better time to become a headphone listener.

SMSL put the same 24 Watt ultra-low-noise power supply they used in SP200, it is encapsulated inside a metal shell and that is fine by me. As with all THX AAA designs, the electrolytic caps are not in the signal path but are used for power filtering and storing.

Test Equipment

SMSL SH-9 was used with two distinct headphone setups. Firstly, it was connected to my reference D/S DAC – the Matrix Audio Element X, where SH-9 was driving some very sensitive IEMs like FiiO FA9, FH7 and Meze RAI Penta. In the second setup SH-9 was connected to an Audiobyte HydraVox + HydraZap, driving much heavier loads like planar-magnetic headphones, ranging from Hifiman Arya, Susvara, Audeze LCD-4, Kennerton Wodan and Erzetich Phobos. I will be comparing it to the Benchmark HPA4 in the latest chapters of this review, so be sure to read until the end. Okay everyone, time to hit some eardrums.

Sound Performance

I. Preliminary Impressions

Oh, it is definitely performing like an Achromatic Audio Amplifier, as no matter the source and the headphone I’m using, I’ll be listening exactly to those two and not to the amplifier itself. It is extremely transparent and detailed sounding, so much so that it pushes to the limits my hearing abilities. The fact alone that I needed a substantial amount of time to differentiate this one from my beloved HPA4, tells how much better SH-9 is sounding compared their previous attempt: the SP200.

Out of all THX based amplifiers I’ve tried, SP200 sounded the most upfront and a bit unpolished with IEMs for example, but I cannot say the same about the SH-9. In my 3-way THX comparison, SP200 went slightly ahead compared to the Drop-789, but at this point there is no contest that SH-9 is a better unit at repelling noise, it has a much higher signal-to-noise ratio and a lower total harmonic distortion.

I am having a very strong sense of Deja-Vu in here, because it really sounds very much like my own amplifier and I will be very hard pressed in a blind-test guessing which is which. The immediate impression with SH-9 is that nothing is standing out in front of the music, nothing is being added to it, nor nothing’s subtracted. It is just the music and the sound signature of your headphones, of your DAC and that is pretty much it. I’m liking transparency in its purest form, I like detail retrieval, I like layers of music and SH-9 got that is spades. I don’t find it bright sounding at all, I don’t find it clinical, it is not really coloring my music and this is pretty much how I would summarize the sound of SH-9 in a nutshell. Power reserve felt huge, it’s exactly the same I’m having on HPA4, it will drive any headphone at its maximum potential, with the exception of Hifiman Susvara of course.

When everything is experienced at such a high level, fluidity will make an appearance in your music, binding the notes together creating a good flow and awakening emotions. You know, when an under-powered amplifier is trying hard to push some planar-drivers, everything would feel lightweight and closed-in sounding, but that didn’t happen with SH-9. With the right music it had authority, a heavier tonality and with lighter music it was softer and smoother sounding.

A super-wide bandwidth amplifier like this one, will offer an instant amplitude to the drivers and will have an immaculate control over them as well. It’s one of the standouts of the HPA4 that carried over to SH-9. They both are extremely fast, hard slamming, but can also be gentle and soft with some other tunes. It’s always changing to your music and to your headphones and that is probably the highest praise I can give to both units.

II. Noise Floor

Most of the desktop headphone amp manufacturers are struggling hard in offering a unit that works equally well with low-sensitivity planars and with high-sensitivity IEMs. Benchmark HPA4 was the first amp I ever tried that was noiseless with all my IEMs, then Sparkos Labs Aries came after that performed the same, then Topping A90 and L30 followed with their extremely clean sounding NFCA modules. SMSL tried hard with SP200 but failed in delivering a noiseless performance with IEMs as it would add some gremlins at higher listening volumes. Even high-end DACs with headphone outputs are struggling offering clean sounding HP outputs, take my reference Matrix Element X and Audiobyte HdyraVox as very good examples, they worked nice with desktop headphones, but not so much with sensitive IEMs.

This time around, SMSL invested a lot more time in R&D, that network of relays you will normally see in high-end amplifiers paid-off big time by offering a perfect channel balance and somehow lowered its the noise floor even further. The fruits of their labor speak for themselves as it sits now at just 1.9 micro-Volts! That is pretty much the same one I have on HPA4…very impressive.

I have several ultra-sensitive IEMs, FiiO FA9 is by far the most sensitive especially when I’m engaging its high-sensitivity switch to on position. No matter how hard I’ve tried, be it on Low or High gain, be it 0 or 99 (Max) volume, I couldn’t spot any noise whatsoever or any traces of it. Absolutely nothing, just a pitch-black background. At normal listening levels, obviously a perfect silence between the notes can be observed and it worked absolutely flawless with all IEMs. Engaging the Kennerton Gjallarhorn which so far is the most sensitive desktop headphone I’ve tried, the same story repeats itself as even on the 4-pin balanced output, on high gain and maximum volume, there is an eerie silence like the amp is not even powered. When you test that for yourself, please be extra careful with the play button or with the backspace key, or you will go deaf on a microsecond.

Volume wise, the highest I could go was 40 out of 99 on the low-gain position, or 25 on the high-gain on the 6.35 mm (1/4”) headphone jack. I personally recommend using the low-gain position, only because there are more steps to play with until you reach your desired volume level.

III. Resolution & Transparency

This is easiest chapter to write about as SH-9 and the rest of THX-AAA gang are extremely clean, transparent to the source and uber-detailed sounding. For the first time in history of Hi-Fi, the bottleneck wouldn’t be the amplifier itself as it usually happens, but the digital or analog source. With a signal-to-noise-ratio of 137 dB, you will need to upgrade to some bat ears to hear additional details in your music. There were of course small differences between all those THX designs that I’ve tried before and from all of them, SMSL SP200 was the least clean sounding, mostly because it didn’t had a pitch-black background. SH-9 completely solved that issue and I feel that an additional layer of information was unlocked, opening wide its windows and letting the music come.

I’m a bit sad, but also super pleased at the same time, that you be experiencing absolutely the same performance I’m having out of the Benchmark HPA4 at just 1/10 of its price and that is mind-blowing just to think about. There is simply a no better time to be a headphone listener.

SH-9 is pretty much a wire-with-gain amplifier, that is achromatic and moves away from your acoustic chain, letting the music do its thing. In terms of resolution and transparency, I’m placing it at the highest level, together with $3000 Benchmark HPA4, with the $2495 Sparkos Labs Aries and with the $500 Topping A90.

There is a wrong trend going online, that to a super-detailed and transparent sounding amplifier are immediately attributed words as clinical, bright, soulless or boring sounding. In my experience, listening to a lot of headphone amplifiers and experiencing some of the best ones and everything in between, I can honestly say that absolute linearity, absolute transparency and detail retrieval is not about being bright, boring or clinical sounding, SH-9 was anything like that.

IV. Transient Response

THX-AAA-888 modules are very-wide bandwidth (0.1 Hz to 500 kHz) mono modules capable of outputting some impressive 6 Watts and 1.5 Amperes per channel at full power. The fastest sounding amplifier that preserved the transient response in its entirety was the HPA4. It was lightning fast with some particular music, it was hard-hitting and very engaging. With it, I could perfectly hear the leading edge of double drums and the shimmer of the cymbals and I’m experiencing basically the same with SMSL SH-9.

When you move away background noise from your music, boost its transparency and lower its total harmonic distortion to inaudible levels, it would be normal experiencing an impeccable amplitude, speed of delivery and an instant decay of the notes in a fast-executed track. SH-9 has a small footprint and its really lightweight and it this regard it really feels like a race car. Once it accelerates, it will keep up with the most demanding tracks, with the fastest beats and with the best drummers out are. I’m going as far and say that it feels considerably snappier sounding comparing to the Drop THX 789, having nimble tempo all the time.

Considering that its output impedance is close to zero, the whole damping factor is fully preserved with both low and high-impedance headphones, meaning that nothing will be stopping those headphone drivers. It is like driving in a hyper-car on an empty highway.

Speed is one thing, but the slam that follows is something else my friends and I can complain only about its slam that didn’t deliver the hardest punches like HPA4 and Flux Labs Acoustics FA-10 delivered in a high-end desktop setup. I’m not sure what is at play here, maybe that smaller 24W power supply was the culprit in here, maybe its smaller capacitance, I’m not really sure, but it didn’t deliver thunder-like eardrum hits with my electronica and rock tunes and this is basically the first complain I have with it.

V. Soundstage & Depth

SH-9 delivered a decent air mass in my tracks, soundstage was not artificially enhanced as it usually happens with tube-based amplifiers. It sounded quite wide and airy to me with a precise pin-point location of all the notes around the listener. Live recordings sounded big, decompressed and quite expanded, especially with open back headphones everything felt outside my head. On the other hand, some older-jazz and some modern rock tracks, felt a lot more intimate, much closer and up-front sounding.

Overall, it has an above average soundstage size on all axes and this is my second and my last complaint I have about this unit. It has a medium sized-stage that will not push a tremendous amount of air around the notes. In this regard, HPA4 went slightly ahead as it is by a little more holographic and 3D sounding to me. I’m blaming it’s switching power supply and its small capacitance that can’t store a lot of power for some nicer dynamic swings. I’m dreaming about a day when a THX-888 amplifier will be unveiled having a much higher capacitance and being powered by an oversized toroidal transformer, that would really make me happy. A design like that will surely push more air around and deliver a much nicer slam for harder to drive headphones like Audeze LCD-4, Abyss AB-1266 TC and Hifiman Susvara.

On the other hand, SH-9 had a very good see-through depth, that carefully placed all the notes in the scenery, so that I could easily appreciate their location and their distance from me. It was able to render the smallest spatial cues, presenting a clear and defined depth to the listener.

VI. Power Output

I don’t need to write much about powering portable over-ear or sensitive IEMs, as SH-9 was able to drive them all on its lowest gain setting no problem.

Moving on to dynamic headphones likes Fostex TH909, Kennerton Magni and Erzetich Mania, 40 out of 99 on the volume wheel was plenty enough to go deaf, it was an easy-peasy task for it.

When it comes to more serious headphones like Erzetich Phobos and Kennerton Wodan planar headphones, the highest I could go on its balanced out was 50 out of 99. There was a lot of power to spare, headroom felt bottomless and no matter the track, it was able to drive them at their maximum.

Upping up the game with something more difficult like Audeze LCD-4 and Hifiman Arya, the highest volume I could go was 70 and again the headroom felt bottomless, dynamics were very impressive, it didn’t show signs of a lack of grunt. I was able to drive them to their maximum and there is nothing more to say about it.

The only headphone that wasn’t driven at its maximum, was the infamous watt-eating, current-drinking Hifiman Susvara. With louder tracks, 90 out of 99 was pretty decent sounding and with very high dynamic range tracks, maximum volume was not enough. While Susvara sounded pretty good with it, it wasn’t offering the best dynamics, it wasn’t a very enjoyable experience. You should also know, that so far not a single headphone amplifier could drive these exactly as I want. I am currently driving them with a 130-Watt power amplifier called Keces S300 and when I want the craziest bass delivery, I’m going with a Kinki Studio EX-M7 power amp – that’s a 25 kilo, 250-Watt beast.

With all that said, anything except for Hifiman Susvara, AKG K1000 and Raal SR1A, should be properly driven with a lot of headroom to spare, don’t you worry about that.

VII. Frequency Response

This will be a very easy chapter, because SH-9 is pretty much the definition of linearity, of a straight as a line frequency response, it’s the most linear and neutral headphone amp you could possibly have and from the lowest sub-bass levels to the highest peaks in the treble, it will render all that without flexing a muscle.

Sub-bass goes low, it is super tight, impactful and really fast and snappy sounding all the time. It has a very clean and breathing type of bass. If you love layers of base, there are plenty of them in here, just makes sure your headphone can show them to you. Its very linear in here and it comes to play only when it is called for. I went through several playlists, one of which consists only of electronica music and with it SH-9 reminded me very much about my own HPA4 with its ride-fast die-young personality, it was pressing down the gas pedal, pumping good vibes and positive emotions all the time.

Mid-bass is pretty much the same, it isn’t over-emphasized, it doesn’t have any rises or drops in here, just a perfectly neutral mid-bass rendition, that is still engaging and very present. With something like Audeze LCD-4, it felt quick and tactile, with a nice impact, plus a faster decay.

Midrange has a decent amount of weight and presence; voices were rendered real and had the right pitch. I felt naturalness too, but only with some particular tracks. At first it might appear as too neutral to a point of being boring or clinical, but in time it was able to alter its voicing depending on the tracks that I was listening to. It went from bright to warm, to neutral and it will be changing its voicing a lot depending on your gear and on the music. On the other hand, you will not find an overly smooth or warm presentation of the mid-tones, those aren’t saturated in here, warmth would appear only when it is called for. If you would like more warmth, you should probably look at your source or headphones or pick another amplifier, because SH-9 is a colorless one.

Treble goes sky high and nothing can stop it. It is rendered perfectly even past top octave. There is driver movement past 16 kHz, especially with Hifiman Susvara. It felt always crystal clear, having an outlined leading edge. The best treble rendition I’ve heard only on THX and NFCA amplifiers and SH-9 feels no different. SH-9 rendered cymbals in a very clean manner, you can feel that metallic shimmering, tambourines were also playful and defined in folk-rock and jazz tunes.

VIII. A Comparison

Benchmark HPA4 ($3000/€3500) VS SMSL SH-9 ($290/€320)

I will say it from the start that if you are interested in driving headphones only and you have just a single DAC, then you should stop right now, get the SH-9 and be done with it. Performance wise, SH-9 is very, very close to the HPA4 with just some minor differences that were observed only with high-end headphones. People that are interested in HPA4 would probably use it in a speaker setup too, it is still the best preamplifier bar none I’ve tried and don’t forget that it has 4 analog inputs! Two single ended and two balanced inputs. It’s so easy comparing two or even four DACs with HPA4. Via its graphical user interface, I can volume match each analog input so that I would have the same sound pressure level with 4 different DACs. All my DAC comparisons were done via HPA4, it is not only a headphone amp, but much more than that, hence the huge price difference.

SH-9 doesn’t have analog outputs, thus can’t be used as a preamplifier, its sole purpose is driving headphones and unleashing their maximum potential without coloring anything in its path. I got used to that touch screen of HPA4 so much, that I want that feature on every headphone amplifier. While SH-9 is not having a touch screen, it has a nice colorful LCD screen that will show all the important stuff as the selected gain, input and volume level. In this regard, SH-9 feels like a huge leap forward compared to any other mid-tier THX-based headphone amplifiers like those of Drop and Monoprice. Its relay-based volume control is an amazing new feature that was borrowed from the HPA4. Of course, the relay count dropped from 24 to just 9, but that is less important because the volume is always volume matched and it isn’t dropping bits of resolution as it happens with regular volume pots. This is where SH-9 plunged ahead compared to SMSL SP200, Drop THX 789 and Monoprice THX 887.

I can say with confidence that SH-9 should easily outperform all those units in a controlled environment, by using a high-end source and headphones. Unfortunately, I can’t do that as my loaner units returned back to their owners.

Compared to the mighty HPA4, I’m spotting the same sound signature, the same linearity, the same extreme resolution and transparency. SH-9 is the third amplifier that is reaching the same resolution level of HPA4 at only 1/10 of its price! I’m very serious about this, you can finally experience the last drop of information and resolution out of your tunes at only $290/€320, something that I could never say about its predecessor SP200 and about the Drop-789. Its tempo is the same, it sounds as fast and decays in the same manner, it also disappears from your music and doesn’t leave any stains.

If I would engage my electronica playlist, HPA4 would have exactly the same speed, but a nicer impact and slam into my eardrums. It was more visceral and engaging sounding, but I’ve felt that mostly with Audeze LCD-4 and with Kennerton Wodan. HPA4 had a slightly higher dynamic range, because it moved more air in the sub-bass departments, improving the kick that followed. With less impactful music, I didn’t observe much of a difference. Another minor change happened when some live recording started playing, where HPA4 would push notes flying to the abyss, decaying easily and naturally. With SH-9, those would drop in their intensity faster creating a smaller soundstage size. For example, live version of Hotel California by Eagles (Tidal / Spotify) was an absolute delight with HPA4, as it was able to decompress everything and place all those notes very precisely in the scenery. SH-9 was by a hair shier and didn’t push those notes as far, everything happening closer to me, it was more intimate sounding by one or two rows.

Apart from those minor details, SH-9 is closely mirroring the HPA4 performance down to the smallest details and that tells a lot about the unquestionable high value of the SMSL SH-9!


I can’t complain much about the SMSL SH-9 performance, but I can tell plenty of things I liked about it. It carries the highest performing THX-AAA-888 modules, some of the best relay-controlled volume pots, it offers plenty of power even for the most demanding headphones. Thanks to its noiseless background, it worked equally well with über-sensitive IEMs as well as hard to drive planar-magnetics. Its bright LCD screen and remote control are coming in handy when using it in a bedroom setup. Most things I’ve said about the Benchmark HPA4 in its review, can be said about the SMSL SH-9, it is really that close. In terms of value, SH-9 just outperformed that awesome sounding Topping A90. It really deserves my highest recommendation if you like your music undistorted and uncolored. I will be awarding it our prestigious Silver Award, as I don’t think you can do much better, especially at this price point.

Congratulations to the SMSL team and I hope to test that SP400 quad-mono, true balanced headphone amp somewhere in the future.

SMSL SH-9 was kindly provided by Apos Audio, it can be purchased from their web-store by following this link (Apos is offering free shipping in the USA, free 30-day returns in case you don’t like it, an extra 1 year of warranty and they will price match any price you can find online).

If you get one, please come back and leave a comment, I’m curious to know how it performs in your headphone setup!


  • Beautiful, sleek looking device
  • Great build quality with an uni-body case
  • Linear frequency response and super extended at both ends of the spectrum
  • Colorless sound signature, invisible in your acoustic chain
  • Most impressive levels of transparency and resolution, it is a detail monster
  • Precise pin-point imaging
  • Excellent dynamics, pace, rhythm and timing
  • Lacks background noise and distortion at any volume levels, great for IEM listeners
  • Plenty of power even for hard to drive planar-magnetics
  • As of right now, it’s your best value


  • Not the punchiest amplifier
  • Soundstage size could be bigger on all axes
  • Would like to have a secondary XLR input


  • Sources: Xiaomi Mi 9T Pro, Corsair One i160
  • DACs: Audiobyte HydraVox + HydraZap, Matrix Audio Element X, Flux Lab Acoustics FCN-10, Burson Conductor 3X Performance
  • DAPs: Shanling M6, FiiO M15
  • Headphone Amps: SMSL SH-9, Benchmark HPA4, SparkoS Labs Aries, Flux Lab Acoustics FCN-10, LittleDot MKIII SE
  • Power Amps: KECES S300, Kinki Studio EX-M7
  • IEMs: FiiO FA9, FH7, Meze Rai Penta, Rai Solo, LittleDot Cu KIS & lots of other lower tiered ones
  • Portable headphones: Sennheiser Momentum 2, Meze 99 Classics
  • Full-sized headphones: Hifiman Susvara, Hifiman Arya, Audeze LCD-4, Erzetich Phobos, Erzetich Mania, Kennerton Wodan, Magni & Gjallarhorn, Quad ERA-1, Ollo S4X Reference
  • Loudspeakers: KEF Reference 3, Buchardt S400
  • Interconnects: QED Reference (x3)
  • Speaker cables: Kimber PR8, Audioquest Type4
  • Power Cables: Isotek EVO3 Premier (x3)
  • Balanced Isolation Power Conditioners: PLiXiR Elite BAC400

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