Frequency Response –
Testing Methodology: RMAA via Startech External Sound Card
The SH-9 offers a linear frequency response through the audible spectrum, an ideal result. This suggests that it adds no intentional coloration to the sound in line with THX’s marketing material. 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 –
I’ve always had a good experience with THX AAA devices here, the 789 and new Fiio Q5 both providing a good range of power in addition to essentially non-existent noise. The SH-9, unfortunately, is a bit noisier than these units, albeit hardly a noisy source in isolation. Plugging up the Campfire Audio Ara (8.5 ohms, 94dB), my usual test for these qualities, I did notice background hiss that was audible without music and still slightly audible with low volume music playing. For most listeners listening at moderate volumes, the noise will be quiet enough not to become apparent when music is playing even on the most sensitive in-ears. In addition, the noise is quite low-frequency so less irksome than some. And, with less sensitive gear such as Dynamic Driver IEMs of headphones, the SH-9 is dead silent. Still, do consider that many competitors do now offer a black noise floor such as the THX789 and Topping A50s.
Output impedance is rated at near 0 ohms which is surely a redeeming quality regarding its performance with sensitive monitors. And in listening, I found this to be an outstanding aspect of the SH-9. This isn’t a specification that most gear will benefit from relative to the majority of high-quality solid stage amps with nigh 1-ohm OI, but can make that last iota of difference. The Ara especially can discern between 1 and sub 1-ohm sources due to its very low impedance and mechanical crossover design. It sounded noticeably more balanced from the SH-9 compared to the THX 789. This surely increases the versatility of the SH-9. Furthermore, I have seen other reviewers dubbing this a noiseless source so long as you aren’t a very low volume listener like me, it is very likely that you won’t notice the background noise I did.
Driving Power –
The SH-9 has heaps of output power but as always, this does not tell the full story with regards to dynamics and the general listening experience. Like the A50s I reviewed recently, I found the SH-9 to be a more linear source with a slightly lighter note weight. I still found Drop’s THX AMP had a bit more power and gusto in its musical delivery, with the SH-9 being more linear and slightly less dynamic. It isn’t lacking per say, but the differences are evident when comparing directly with larger desktop sources likely due to the difference in power supply size and design. Nonetheless, this is mostly felt on full-size headphones, IEMs I found to be well-driven, the majority with zero background noise and great fine-grain volume control down to very low volume levels.
Switching to the balanced output revealed a very similar experience and no volume difference given that the power output is the same as the single-ended output. If I had to pinpoint a difference, I would say the soundstage was a touch wider and the imaging slightly sharper, however, it was minute. That’s not to say there is no benefit having the balanced capability here as it does increase versatility. So, I suppose we can look at this as having the full experience through the single-ended output too which is surely not a bad thing for the end user.
Testing Methodology: SPL volume matched AB with HEDDphone connected to in-line splitter between THX 789 and SH-9 both connected to SMSL SU-9 with RCA splitters.
The SH-9 offers a very linear and balanced sound as you would expect from a good solid-state source, especially one featuring THX’s AAA module. As always, with source reviews, the extent of the change between linear sources when impedance is disregarded is far less than you would encounter between headphone to headphone. However, subtle colouration is evident on each model.
With the SH-9, I found the experience fairly reminiscent of the NFCA-based Topping A50s I recently reviewed. In particular, the SH-9 appears to offer a very flat and honest sound albeit one with slightly lower note weight. To preface, I do not consider this a bad thing at all, rather, a matter of preference and synergy with the DAC. The SH-9 has an especially clean presentation with a very natural tone and notably strong detail retrieval. It also manages an impressive soundstage at its price point. It also represents an excellent foil to the slightly lush and smooth SU-9 whether intentional or not. The net result is a very natural sounding stack that feels well-rounded from top to bottom. Of note, the THX789 remains my benchmark amplifier around this price range because I purchased it myself and also since I feel it represents a very well-rounded experience despite no longer holding the measurement crown.
Compared to that amp, the SH-9 provides a slightly lighter note weight with a little less slam and physicality in the sub-bass in addition to an uptick of body in the mid-bass to compensate. In turn, it comes across as just as full and with a slightly warmer and, subjectively, more inviting tonality. However, it also isn’t as hard-hitting or dynamic in its delivery as the Drop amp, especially noticeable on bassy tracks. The 789 also has slightly faster attack or, perhaps simply the impression of it, which gives it a more aggressive and high-energy presentation. Meanwhile, the SH-9 is a bit more composed and refined in its delivery, with slightly quicker decay and a more rounded note body. It is highly controlled and a bit more defined in the mid-bass than the 789, granting it an advantage when it comes to timing and deconstructing complex tracks. Otherwise, expect a linear and natural voicing with an accurate timbre on both. Neither amp I find to be especially coloured in isolation, though the style of note presentation does differ to some degree.
We can observe a similar trend in the midrange, though the Drop amp actually has a slightly softer note presentation here. The SH-9 is a very slightly brighter source with a hint of additional upper-midrange energy. This is compounded upon by its slightly lower note weight producing a revealing, open and clear sound with strong definition. The THX789 sounds a bit smoother, denser and fuller, sacrificing some of that definition for stronger coherence and a more powerful vocal reconstruction. Meanwhile, the SH-9 is more delicate in its approach, with better extension and a bit more space to play with. Both are also articulate sources; I find THX amps to have a little more bite than most in the lower-treble which contributes to this impression on both. Still, from a tonality point of view, the SH-9 is a highly neutral source much like the THX789. It isn’t obvious in its colouration, just a hair on the revealing side which, again, makes it a strong pairing to SMSL’s own SU-9.
And up top the experience is once again quite familiar. The SH-9 offers a bit more lower-treble bite than pure neutral but not with any emphasis or brightness, rather, a clean and sharp transient response. This gives it strong fine detail retrieval in the foreground slightly better, in fact, than the THX789. I also find it sounds a bit more refined than that source, being a hint smoother and more natural in its voicing. The SH-9 has a clean, even background too but a lick of upper-harmonic boost that imbues an ear-tickling sparkle. Accordingly, micro-details pop a little more, especially in front of that dark background, and this serves to further reinforce its generally strong detail performance in class. The SH-9 has great resolving power and doesn’t fatigue at all despite having an uptick of energy at the very top.
The SH-9 provides a well-rounded soundstage for its asking price, a pleasing combination between great width and good depth. This is key as I find many midrange amplifiers to provide good width but not as much depth as the SH-9 which helps greatly in providing an involving sense of location. Its imaging too excels, it was a little sharper and more multi-dimensional than the THX789 and Topping A50s too. While all sources are quite sharp, the SH-9 had noticeably better layering and slightly more accurate localisation and distance portrayal. It has great separation on behalf of its clean, balanced sound profile and slightly thinner note body which helps pinpoint small details – For the money, no complaints here.