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s.m.s.l SH-9
THX AAA-888 Headphone AMP
THXAAA-888 Headphone Amplifier with THX AAA Technology；
6 Watts into 16 Ohm, 3 Watts into 32 Ohm Headphones with lowest THD+N ；
0.1 Hz to 500 kHz(-3dB) Frequency Response ；
SNR＞137dB ;
THD＜0.00006% ;
Ultra-Compact Design, Perfect for Desktop Systems；
Balanced Stereo Headphone Output ；
Balanced Stereo Line Input；
High Precision Resistors for Temperature Stability ；
Pop-less Design with High-Quality Relays；
High precision and low noise 256 level relay volume control；
*In actual use, in order to make the volume more linear, the extra levels are shielded.
2 Positions Switchable Gain Control ；
Fully Protection with DC, Over-Voltage, Over-Current, Short-Circuit and
Thermal Protection on Headphone Amplifier ；
High-Efficiency Ultra-Low-Noise Power Supply .
1.9 inch LCD display
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s.m.s.l SH-9
The s.m.s.l SH-9 is a compact THX‑AAA‑888 headphone amplifier that pairs near‑reference transparency with surprising headroom. In his review, Sandu Vitalie found it largely invisible in the signal chain—ultra‑detailed, neutral and revealing of source/headphone character. The SH‑9 excels with a pitch‑black noise floor (IEM‑safe), lightning‑fast transients and excellent resolution, while offering up to 6W into 16Ω and balanced outputs for demanding headphones. Its CNC‑milled matte chassis, 1.9" LCD and relay‑controlled stepped volume add desktop polish and practical control. Ideal for audiophiles who want honest, high‑resolution playback from sensitive IEMs to planars, and for budget‑conscious listeners seeking HPA4‑level clarity. For the price, the SH‑9 is a standout value that prioritizes neutrality and transparency.
Pros
- Reference-class transparency and resolution — reviewer reports an ultra-detailed, ‘wire-with-gain’ neutrality that lets source and headphones shine.
- Extremely low noise floor and IEM-friendly performance — pitch-black background suitable for very sensitive monitors.
- High-quality build and control — CNC-milled chassis, 1.9" LCD, remote control and a relay-controlled stepped volume for precise, low-noise adjustments.
- Strong power delivery and balanced outputs — up to 6W into 16Ω with ample headroom for most planar and dynamic headphones.
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Cons
- Not the punchiest amp compared with top-tier references — reviewer notes slightly less slam than the Benchmark HPA4 and some high-end rivals.
- Soundstage is very good but not as expansive or holographic as the highest-end references.
- Limited analog connectivity and no preamp outputs — only one balanced XLR and one RCA input on the back.
Sound Quality
90/100
The amp is reported as extremely fast with strong slam and punch, capable of both hard slamming and gentle nuance. The reviewer notes the slam is slightly less forceful than reference units (Benchmark HPA4, Flux Labs FA-10), so dynamics are excellent but not the absolute top of the class.
Noise Floor
92/100
Review explicitly states 'I couldn't spot any noise whatsoever' and 'just a pitch-black background', plus an SNR of 137 dB cited — indicating very low noise suitable for sensitive IEMs and full-size headphones. Language supports a near-reference silence though based on a single strong review rather than multiple sources.
Headphone Compatibility
89/100
SH-9 delivers up to 6W into 16 ohms and 3W into 32 ohms on both 1/4" and 4-pin XLR outputs and includes balanced outputs — strong specs for driving a wide range of headphones. Review implies desktop-class power and balanced driving capability; output-impedance specifics aren't listed but THX topology implies low impedance, supporting wide compatibility.
Build Quality
91/100
Reviewer notes 'build quality really nice' with 'close to zero complaints' and highlights a high-end relay-controlled stepped volume attenuator. The presence of a stepped relay volume and solid chassis design are consistent with a well-built desktop amplifier.
Features Connectivity
87/100
Back-panel balanced XLR and single-ended RCA inputs, universal AC inlet, relay-controlled stepped attenuator, and both 1/4" and 4-pin XLR headphone outputs provide a strong feature set beyond the minimal baseline. No DAC or digital inputs are mentioned, so features stop short of full streamer/DAC functionality.
Value for Money
93/100
Reviewer repeatedly praises value — calling its performance comparable to a Benchmark HPA4 at roughly 1/10 the price and stating 'it's your best value' and 'mind-blowing'. Strong positive value language justifies a high score relative to its price segment.
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