SMSL SX-8s Stack Review – DAC/AMP On a Diet

SH-8s Sound Breakdown

Frequency Response –

Testing Methodology: RMAA via Startech External Sound Card

The SH-8s offers a linear frequency response through the audible spectrum, an ideal result. This suggests that it adds no intentional coloration to the sound. Due to the quality of my sound card, I am unable to reliably test other measures such as distortion and crosstalk so they will be used as a personal reference only. Qualities here can impact the sound in subjective listening.

Output Impedance & Hiss –

The SH-8s claims a near 0-ohm output impedance but doesn’t list a specific specification. I tested this empirically using the Campfire Audio Ara (8.5 Ohms, 94dB) which has a mechanical crossover and super low impedance meaning it can discern between even 1-ohm and sub-1-ohm sources. Compared to the THX789 (1-ohm), this was indeed the case, as the Ara had a noticeably bassier and smoother sound from the SH-8s which was in-line with my experience with other sub-1-ohm sources.

Furthermore, the SH-8s had a dead silent noise floor on low-gain on all of my most sensitive IEMs. This was actually a better performance than I found on the SH-9, my biggest complaint with that unit. Perhaps this can be attributed to the use of an analogue pot for volume control, or simply more experienced approach to design. Either way, these results on the SH-8s are both ideal, meaning the amp doesn’t just have a heap of power for headphones, it performs superbly with IEMs too. In addition, the volume pot has barely any channel imbalance right down to zero which gives heaps of granular control for sensitive IEMs, I’m a big fan.

Driving Power –

This is always a difficult section to approach as all modern sources have huge power output numbers and efficiency. However, we must remember these numbers are usually peak figures which is just a snapshot of the overall performance at a single point in time. This means the listed specifications doesn’t necessarily speak for the actual musical performance which makes it very difficult to purchase an amp simply going by these specific measures. As far as volume is concerned, you will never have an issue on the SH-8s, there is plenty of voltage on tap when using high-gain.

When it comes to dynamics, it scores a firm “good” in my books. The SH-8s has a good amount of depth that is a clear improvement over smaller amps around its asking price such as the A50s. However, it doesn’t quite have the power and boldness of the THX789 which is my personal benchmark around this price. This isn’t hugely apparent but noticeable on AB. It is more obvious on complex passages such as my usual test track “lateralus” by TOOL. I found the amp would lose some composure on sub-bass heavy passages with double bass drums where amps like the A30 Pro and 789 were keeping pace better.

Subjective –

Testing Methodology: SPL volume matched AB with D8000 Pro connected to in-line splitter between THX 789 and SH-8s both connected to SMSL SU-9.

The SH-8s has a clean and calculated sound. I am finding myself doubting my ears with many of the new THX, NFCA-based and now PLFC-based amplifiers as they all have a very similar character overall – that being, a highly linear, achromatic sound. So do take note of the small extent of any colouration mentioned below. Some may consider this to be a slightly bright leaning source, to my ears, this comes in the form of a slight middle-treble forwardness. This means treble instrumentation generally sits slightly further forward in the mix. The SH-8s also has a more vivid midrange presentation and an uptick of contrast leading to a slightly leaner note weight but also enhanced clarity and definition. This is counterbalanced by an uptick of mid-bass fullness that grants a punchy, full character. While it isn’t an especially large and substantial sounding source, it is balanced and free of glare or sharpness. Dynamics and responsiveness both operate at a good level too, retaining an engaging listen in the absence of huge colouration.

Bass –

The SH-8s will divide in two regards; it is not a weighted and dynamic amp, but a responsive and articulate one. Accordingly, those wanting a grand sound with an emphasis on rumble and slam may be left wanting. Focus centres rather around the mid-bass which enjoys a small hump with a tight albeit less present sub-bass below. The upper-bass appears to taper off slightly entering the lower-midrange, meaning this isn’t an obviously warm-leaning source. The note presentation is of most interest; to me, this is the defining characteristic of the low-end. It has a very responsive and well-defined presentation with excellent control and tightness. Furthermore, the slightly reduced sub-bass lends additional separation to the mid-bass. Combine this with assertive, concise note attack with quick decay, and the amp rewards with a pacey and highly articulate presentation. This works well in tandem with its slightly fuller tuning to provide an especially punchy and tactile sound that retains impact and convincing body. Though not the most deep and dynamic sound, this will please those wanting an especially fast and well-textured bass.

Mids –

Many similarities continue through the midrange. Once again, this isn’t a powerful and rich sounding source but a slightly lean, clean and vivid one. As bass isn’t emphasized overall and there’s a slight dip for contrast above the mid-bass through to the lower midrange, the midrange itself benefits from a neutral tonality. Additionally, the slightly leaner note body instigates its more vivid and revealing character. This works in tandem with its lifted top-end, drawing focus to articulation and enhancing definition and clarity. However, this does come at the cost of a touch of dryness in its voicing, assuming a breathy, raspy character most noticeable on modern pop tracks. To reiterate, this is most noticeable when ABing with other amplifiers and isn’t big enough to compromise listening on its own, it is something to note for specific pairings. Altogether, I remained impressed by the voicing and resolving power on offer. Resolution is as good as any other THX source and the vivid voicing draws further focus to fine textures and details. While this comes at the cost of slightly reduced power and gusto, the amp has increased vocal size and neutral positioning that upholds a natural listen. As with all colouration, the key lies in moderation and consistency, both of which I feel are upheld here with aplomb.

Highs –

The top-end sits just a hair forward relative to the rest of the presentation which I would say is chiefly responsible for its overall vibrant expression. This is mostly centred around the middle-treble, leading to a lift in brilliance, shimmer and zing. As the lower treble hasn’t been brought forward, instruments aren’t too thin or sharp, albeit note body is a touch reduced from neutral. In turn, the SH-8s provides an airy, clean and energetic sound but not an overly textured one. It has a lighter note weight but crafts a convincing sense of atmosphere that adds immersion when combined with its staging performance – more on this later. Compared to competitors like the THX789 and A30 Pro, the SH-8s has a slight bias towards air and shimmer over the initial transient attack. In turn, its note presentation is not as sharp and defined, though I found this to work well considering the airy style of the overall presentation. While I would consider the SMSL to provide similar detail retrieval, it is slightly less aggressive in its delivery. Those two amps provides just a smidge more texture and fine detail but the SH-8s does have a more open sound with a bit more headroom.  

Soundstage –

With a solid technical foundation in the treble, the SH-8s crafts convincing soundstage dimensions. Interestingly, I immediately noted a somewhat depth biased presentation, with a more intimate width but great ability to project. Depth is definitely something in shorter supply and it provides a pleasing sense of dimension and scale to the SH-8s’ performance. However, the lack of foreground/background contrast and below average width so mean layering leaves to be desired. Whilst it has the resolving power to discern many layers, they aren’t especially well-delineated. Otherwise, imaging performance is solid. You get sharp and clear directional cues and a well-organised image.

The lean, well-separated sound heightens this impression. That being said, the lack of width does mean some instruments are pushed closer than desired. The worst-case scenario is on tracks like Fleetwood Mac’s “Dreams” around 1:15, where the backing guitars are both emphasised due to the forward treble and brought more intimate due to the reduced width, creating a slightly intense sound. For the majority of tracks, this is not an issue, but do note this unique fallibility of the SH-8s. Separation does much to redeem this, being a great performer throughout. This is especially so in the midrange, where there is evident air surrounding each note. This draws further focus to small details without introducing additional brightness.

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