SMSL HO200 Review

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NOTE: Subjective impressions and review are written BEFORE measuring the device. I deliberately avoid measuring until I have finalised my subjective impressions to avoid objective behaviour influencing my opinion.

ChitChat:

The HO200 is an affordable, high performance headphone amplifier that offers just about everything one could need from a product in this category.
It is of course a headphone amplifier, fully balanced, with XLR and 4.4mm pentaconn outputs, as well as a single ended 6.35mm output. It also functions as a preamplifier to control your speaker system or daisy-chain to another headphone amplifier.

It offers up to 3w @ 32 ohm power output, meaning it should be able to drive very demanding headphones without issue, and also boasts an incredibly low noise floor that means it’s also an ideal candidate for IEM users who want something that will not have any audible hiss or noise on even the most sensitive IEMs.

If you’d like to see some measurements of the amp, I’ve posted them here: https://goldensound.audio/2021/12/27/smsl-ho200-headphone-amplifier-measurements/

All of this in a compact package under $500 seems pretty enticing, so…how does it sound?

Review:

Build:

The build quality of the HO200 is quite good. The chassis is all-metal with a very nice matte-black finish, and whilst I do slightly prefer the ‘single-piece-of-metal’ design of products such as SMSL’s own VMV A1 amplifier, this does still look and feel satisfyingly high quality.

The toggle switches make it easy to see at a glance what settings the amplifier is currently running, and they feel pleasantly firm and solid with no wobble or play.

The only control that maybe could do with a slight upgrade is the volume knob, as whilst it does look nice with the ridged Fresnel style finish, it does feel obviously plastic when you touch it and it’d be nice to see a metal knob here to complete the design.

The underside of the unit has four hemi-spherical rubber feet, lifting it about half a centimetre and will not cause any worry about damaging anything that you stack this unit on-top of.

And on the rear are two sets of XLR and RCA connectors, one for inputs to the device, and one that act as preamplifier outputs.
The power supply is auto-ranging so no need to fuss with voltage switches, and lastly there is a USB port which allows for updating the firmware of the protection controller. So far no firmware has been released but this may be used in future.

Pairings and Testing:

The HO200 is an amplifier that will comfortably drive the majority of headphones on the market. I was able to run everything including planars such as the Hifiman Arya without feeling that they were at all underpowered, and sensitive IEMs such as the fantastic Moondrop KATO had no audible noise whatsoever even with the pot maxed.

BUT, for the really hard to drive stuff such as Susvara and the 1266 you will benefit from getting something with more power, as the Susvara in particular really does change quite a bit dependent on the power capabilities of the amp you run it on.
Headphones such as the Arya or Diana V2 will have no issue being driven off the HO200 to their fullest extent.

During my evaluation I mostly used the HD800, Hifiman Arya and Moondrop KATO, as these represent a fairly wide spread of types of driver and power requirements.

Sound:

A quick chat about ‘measure-fi’ amps:

In recent years, headphone amplifiers, particularly those at the lower end of the pricing spectrum have come a LONG way.
It wasn’t too long ago that finding a headphone amplifier with decent levels of objective and subjective performance was quite difficult, and usually quite expensive.
However that all changed quite rapidly as we saw products such as the THX 789 and SP200 bringing what was objectively absolutely mind-boggling performance to the masses. And given the runaway success of the THX 789, other manufacturers sought to quickly develop their own amplifiers with a focus on objective performance.

But whilst these devices were clearly quite a step up in resolution and technical ability compared to existing similarly priced amps, many people including myself found that the sound still left a lot to be desired.

The THX 789 whilst resolving, was very bright and harsh (though could be aided with some tweaks to the volume/gain setup), and it wasn’t until a while after when some new products such as the Topping A90 were released and we began to see some amplifiers that kept the impressive objective performance, but offered a sound signature that was closer to neutral with less glare and aggression.

Moving on to today and now there are dozens of products using various approaches to heavy error-correction with objective performance that are in some instances pushing the limits of available measurement hardware.
But an amp having 120dB vs 121dB SINAD is hardly important, what I am enjoying is that these amps are SOUNDING better and better.
That glare and aggression is being eliminated, and timbre is more natural and convincing leading to a much greater overall enjoyment and sense of realism when listening to music. An amp being well measuring is no longer a near guarantee of a ‘clinical’ or ‘sterile’ sound.

HO200’s Sound Signature:

The HO200 is one of the latest of these incredibly well (objectively) performing amplifiers, and it’s been quite interesting spending time with it.
My first impression upon spinning it up and listening through a few favourite tracks was that it is impressively neutral. Having this side by side with a Schiit Asgard 3 and a THX 789, the simplest way to put it is that it would be slap bang in the middle of these two as far as tonality is concerned.
Not as clinical as the 789, but not as warm as the Asgard 3.

‘All of the time’ by Jungle sounded absolutely phenomenal and simply ‘right’. On this track the heavy low-end can often become too boomy and overbearing on warmer amplifiers, sometimes even making it difficult to clearly hear the detail in the vocals or bells off in the distance.
Whilst on some other amplifiers (The ADI-2 inbuilt headamp springs to mind), this track can have the issue of vocals being too aggressive and piercing, not helped in situations where that bass guitar lacks weight and presence to fill out the track.
On the HO200 it was spot on, forward and lush, but letting the vocals shine through with clarity and space.
The HO200 keeps an excellent balance of tonality in this situation.

One aspect that has remained consistently impressive across all of the error-correction heavy amplifiers is how incisive they are. This often came at a cost of being aggressive and fatiguing, but as mentioned above, to my ear this is something that seems to be getting better with each ‘generation’ of these amps, and whatever SMSL is doing with their Precision Linear Feedback Circuit (PLFC) is certainly doing a good job.

‘Information Overload’ By Grabbitz contains a busy mix of synths, crisp vocals and snappy percussion (albeit also synthesized). And on the HO200 every aspect is delivered with precision, force and control. The vocals sit in a confined space of their own, not bothered in the slightest by the pounding, rumbling synths playing around you. Even the strumming of the guitar at 2:38 is so satisfyingly clear and defined.
Throughout the track not a hint of sibilance can be heard and I could happily listen all day long, something that I certainly would NOT be able to do on a 789.

On warmer amplifiers such as SMSL’s own VMV A1 this track doesn’t have anywhere near the technical prowess that the HO200 shows, and leaves a fair bit to be desired. Though the VMV A1’s lush and dense presentation does make genres such as metal and rock music impressively fun.

In terms of the ability to use different headphones on the HO200, I had no issue driving any of my headphones with this amp.
Though the Hifiman Susvara didn’t have the ultra-precise imaging and beautifully tactile low-end that I know it can present on higher powered amplifiers, though this isn’t a fault of the HO200, as so far I’ve only found one headphone amplifier that drove it as well as speaker amps do, that being the Ferrum OOR, which is also considerably more expensive than the HO200 so not exactly a competitor.
But for literally anything else, the HO200 has all the power you need.

On the other end of the spectrum, sensitive IEMs had some problems that I didn’t encounter on harder to drive cans, which I’ll discuss more down below.

But moving to more normal headphones;
The HD800S kept all of its impressive staging ability, detail retrieval, and felt like a very good synergy. The HD800 has often been recommended to pair with warmer amps due to it having a tendency to become sibilant on more sterile source chains. It is indeed quite an amp picky headphone, but it sounded right at home on the HO200.
The HO200’s impressive incisiveness allowed the HD800’s technical ability to be shown off, but thanks to the HO200 not at all being a harsh sounding amp, it always felt comfortable and smooth to listen to at the same time.

On the Hifiman Arya, subbass had excellent extension and definition. Timbre of instruments were spot on, and everything from beautifully recorded tracks such as Fourplay’s ‘101 Eastbound’ to LoFi tracks like Mirage’s ‘Cold Outside’ were engaging, impressive, and the ability to dance from slammy and dense to light and ethereal with such ease was a joy.

But there was one thing that this amplifier didn’t do so well: Soundstage.

Whilst the timbre of vocals on the HO200 was presented excellently, I often found that things sounded closer to me than they should.
‘Can’t Stay Mad’ by Sir Woman is a track that I often use as a quick ‘do I feel like I’m there’ test. On a great chain, a quick listen to this track with eyes closed will have you transported right in the centre of the music. And with the HO200 whilst the detail was fantastic, the drums were tactile and had just perfect levels of decay, and even the brass and strings had absolutely stunningly accurate timbre…it was all just a bit too close to me!
I felt like things were playing around my head, not around the room. And that’s a shame because when slotted into my chain of the Holo May and Hifiman Arya, the HO200 really doesn’t leave the listener wanting for much at all. But I did want some more staging….

And then we come to IEMs. On the HO200 IEMs have the advantage that there is an absolutely dead silent background. No hiss whatsoever on any IEM that I tried. And in low gain there was sufficient volume control to adjust comfortably too. I would have perhaps preferred if low gain was maybe 6dB or so lower just to give a bit of extra pot range when using a balanced dac and sensitive IEMs, but I was never uncomfortable with the amount of control range I had.

But whilst the ‘blackground’ was impressive especially given as many other amps, even very good ones, don’t get close to the SNR that the HO200 offers at IEM listening levels, I did have one issue in that imaging and staging was quite diffused.
This was strange as it didn’t occur on regular headphones, only with IEMs.

I first thought that maybe it was simply an issue with the low-gain setting, but even after running in medium gain this issue persisted.

Listening to the Analog Sessions version of ‘No Words’ by Big Wild, on fullsize cans like the Arya, the vocalist was coming from a distinct direction, focused and clear.
Whereas on IEMs, the direction was quite difficult to discern. The image felt more spread out left to right and diffused.

I’ve no idea why this is, or why it’s only occuring on IEMs. It’s not to any level that detracts from my enjoyment, I’m jamming out to KATO on the HO200 as I write this, but it may be more important to some listeners.

UPDATE: After measuring the device, I’ve found that crosstalk on this amplifier seems to remain at a fixed level, meaning that when running the amp at a lower output level (such as with IEMs), the crosstalk will be relatively higher and this could explain why there is some ‘diffusion’ with sensitive IEMs but not with harder to drive headphones.

Summary:

In Summary, the HO200 is a fantastic amplifier, one that will be a good match with all but the most demanding headphones. It offers an incisive, detailed, forceful and full-sounding presentation. It does fall behind other options such as a Singxer SA-1 in terms of soundstage size and for those who listen exclusively to expansive orchestral tracks that may be a better choice, but for those who listen to anything that demands detail, attack, and engagement whilst preventing sibilance and aggression, the HO200 is an excellent choice.