SMSL SH-9 is a balanced headphone amplifier based on the THX888 chip. It provides 3W through the balanced output and costs 289$.

SMSL SH-9 is a balanced headphone amplifier based on the THX888 chip. It provides 3W through the both outputs and costs 289$.

Sound quality for the price

Rating: 10 out of 10.

Build quality

Rating: 9.5 out of 10.


Rating: 10 out of 10.


THX – nothing interesting? Not this time.

You may think, oh, that’s another amp based on the THX chip, nothing interesting. Well, I won’t lie, my first feeling was the same. All of them are similar, but this one is different. SMSL has changed a lot in their playstyle by the time, from one of the most “digital” sounding devices to one of the strongest participants in the Chi-Fi race.

My opinion about the THX amps has changed after the first listening session, and it changed a lot. Why? You’ll know that after reading the following paragraphs.

Packaging & Build Quality

Only inputs, nothing more.

The SMSL SH-9 was made to be a pair for the SMSL SU-9, so it looks almost the same. The only differences are the headphone outputs on the front and a small THX logo on the top. I’m delicately sad because there are only 4pin XLR and 6,35mm jack outputs on the front. I wish there had been a 4,4mm balanced output implemented as well.
There are only two analog inputs on the rear— one pair of RCA and one pair of XLR.

The overall build quality is excellent. It’s a really solid piece of metal.

The screen has the same colors as the one in SU-9, but it has a more expansive range of brightness settings. 2/6 is the same as 1/6 in SU-9, and the 5/6 is equal to 6/6 in SU-9.
What else can we change using the menu? Not much, but there are all necessary things. To be honest, it has the same functionalities as the switches in the SP200. You can choose the input, gain, the volume mode, and set the brightness.

Almost the same.

The potentiometer has an excellent click, and it’s absolutely correct. Thanks to being digital, there’s no channel imbalance, which is ideal to use with low impedance IEMs or to listen quietly.

Inside the box, you’ll find the same set that comes with SU-9, so only the amp itself, power cord, remote, and some paperology. The producer doesn’t provide any interconnects, even basic RCA. On the other side, if you already have some cables, you don’t pay extra for the ones in the box.

The SH-9 gets really warm during usage with low-impedance planars on high gain, so provide the SH-9 a decent airflow.


THX AAA technology – what is that? That’s a shortcut for “Achromatic Audio Amplifier,” which means the THX involved that standard for amps to be, well, achromatic, so they don’t colorize anything. That makes all the THX AAA amps have the lowest possible THD distortions, set at 0.00006% this time. Keep in mind that the SH-9 isn’t truly balanced. The final power is the same using both outputs, and the balanced input is here just to give you more options.
The chip inside, the THX 888, is the same as the one in SMSL SP200, but the final result is different.
Besides that, it’s the amp that goes great in all possible measures. But how does it sound for real?


Beautiful and simple stack.

Well, that’s a challenging part to describe because the SH-9 provides a really clear and transparent sound without implying much to the sound. As I mentioned at the beginning, I wasn’t genuinely fascinated by the SH-9 at the beginning, because all of the THX amplifiers I’ve heard sounds similar. Dry, dull, correct like Netflix’s tv series. The only similarity of SH-9 is being unbelievably exact but absolutely not dry or flat. And I like that a lot. It provides a lot of fun in every point of this word’s meaning.
If I’d have to say which frequency is the most prominent in terms of sound signature, I would say it is like the podium, where all competitors win the competition.

If you’d like to use the SH-9 with IEMs – feel free to do it unless you have some truly sensitive IEMs, like CFA Andromeda. Using all the earphones I have, I can hear only a delicate background noise that isn’t disturbing for me. I can’t hear that when the music is playing.

The queen and the king.

The bass is a speedy and punchy beast. It strikes from nowhere to disappear in the blink of an eye. It’s perfectly separated from the other frequencies, always keeps its place in the row, which has the same importance as the rest. That’s matched with excellent power in the sound, with nice subbass addition. As you can expect after the insanely low THD+N measurements, it provides a lot of texture that’s not exhausting because it doesn’t bring any dryness. It matches all headphones I’ve tried, starting with the cheap Moondrop SSP, ending with the Audeze LCD-3. Every time it wasn’t overwhelming or indisposed, always perfect and lovely. With that bass, my guilty pleasure is listening to Russian techno, also known as hardbass. I’m afraid the LCD-3 that I use for that will someday say hello to me with beautiful “сука.”

As expected, the midrange also provides a nice texture, but it’s delicately softer than the texture in the bass. As the main difference between the SMSL SP200 or even the FiiO M11 Pro, the SH-9 has some life in it! It isn’t cold, but it easily lets me feel the music, start dancing, singing, and so on. The theme or the headphones I choose doesn’t matter. Whenever I’m listening to SH-9, I enjoy the music and being enamored by all the insanely accurate details. Apart from those in the higher part of midrange, it sometimes lacks vitality, but really rarely. Besides that, I can’t say a bad word about the mids.

Oh, and one exciting thing – with high gain, the vocals come closer to the listener. That’s the most visible using Audeze LCD-3, but it happens with all cans I’ve tried. 

It doesn’t affect the sound signature of a headphone of choice in any way.

The treble is somewhat boring to describe but not to listen to. It’s just absolutely clear, clean, and exact. If the track has correct mastering, and your cans don’t tend to sibilance, you won’t face any. Using AKG K702, sometimes I can hear some sibilances, but only with poor-produced tracks. Using Craft Ears Four, Campfire Vega 2020, or the Audeze LCD-3 – not a single sibilance. Only incredible details and a lot of air. I love how the drum plates sound. When they play, I can even see and feel how they’re shaking. I’m in love with classical music for the last few days, so one quick example with “The Pianist” soundtrack. It sounds wonderful. It provides a feeling of a true piano, no matter what headphones I try. It’s intimate and powerful at the same time.
The rest stays for the headphones’ side. The SH-9 will show you what they truly can.

The soundstage is excellent, but it delicately misses the height. From all the directions, I can hear everything with the sounds that go around my head to swirl into it at the end. And that’s nice. The SMSL SH-9 doesn’t ruin any soundstage, doesn’t provide extra magic and fading, and doesn’t take it away. Only the style that headphones offer, with a delicately lowered ceiling. So, whatever you like in your cans stays here. Do you prefer more exact pinpoints? You got it. Or maybe you want to have more fading and going all-around style of your headphones? Don’t worry, you’ll have that.

It was as useful as the LittleDot MKIV I reviewed a while ago during the gaming sessions. It means the SH-9 is now my best friend for gaming. The directions are way more exact than my friends’ info. 

Low impedance IEM? No problem.


As I mentioned above, the SH-9 matches with every headphone perfectly. So, only if there’s enough power for you, and there should be, you can feel safe putting the SH-9 in the shopping cart. Of course, if you’re looking for a transparent AMP that shows everything that cans want to show. 


LittleDot MKIV is a tube amp, so obviously, those two sound completely different. LittleDot provides a smoother, more analog sound with delicately worse details at the ends of the frequency range but a better height of the soundstage. It is also more natural and delicately calms the headphones. After that, the SH-9 is way smaller, so it’s a better choice if you have limited space.

Topping DX7 Pro (vs. SH-9 paired with SU-9) has a colder sound, slightly worse microdetails in the midrange, and a soundstage placed way closer. The height is similar, when the width closes faster, it has the same exaction level.
It also provides less power and has a more technical playstyle, which delicately increases the overall sharpness. But it is 100$ less, and you don’t need any external cables. I love both the DX7 Pro and SMSL combo, but I would rather choose the SU-9 and SH-9.


Simple yet elegant. Ear Fidelity approved.

The SMSL SH-9 is a beautiful AMP that has no weak points in the sound. A lot of details, being transparent without cutting off anything, letting the headphones be how they are. So, we have an excellent build quality, a lot of power, and it pairs with all headphones I have perfectly. For me, it sounds like an absolute amp. If you watched 3rd part of Star Wars, you probably know the verse “Only a Sith deals in absolutes”, and that amplifier will deduce you from the mistake.

Absolutely recommended.

Disclaimer: SMSL SH-9 was sent to us in exchange for an honest review by Apos Audio – Thank you!

This review is my unbiased opinion, and it wasn’t influenced by anybody.

You can get your SMSL SH-9 here.

Gear used during this review for the sake of comparison and as an accompanying equipment:

  • Headphones – Philips Fidelio X2HR, Audeze LCD-3, Craft Ears Four, Hifiman HE400i 2020, AKG K702, Campfire Audio Vega,
  • Sources – Chord Mojo, iFi iDSD Neo, Topping DX3 Pro, EarMen TR-Amp, iDSD Signature, Topping D50s, FiiO Q5S, DACAMP L1, LittleDot MKIV