SMSL SH-9 Amp Review Compendium

Compendium Last Updated: Nov. 21, 2020

As reviews for the SMSL SH-9 THX AAA-888 Balanced Headphone Amp start getting published, we will be reading and compiling them all right here for you, so you can get the latest influencer opinions all in one easy-to-read spot. You can get the link to the original posting in the headline for each article; otherwise, some reviews have been edited for conciseness and clarity. Enjoy!

1) Audio Science Review’s piece on the SMSL SH-9 Amp, originally posted on Nov. 13, 2020.

The market for high performance headphone amplifiers has become quite crowded but SH-9 sets itself apart with a gorgeous digital display and volume control.

A 256-step attenuator using resistor ladder implements volume control which should result in perfect channel matching (see measurement later).

SMSL SH-9 Measurements

As usual, we measure the unity gain of the unit with feeding it 4 volts and getting 4 volts out. The low gain mode is 0 dB which makes this task easy:

SMSL SH-9 Measurements.png

This is superb performance and provably transparent to the source. Ranking is way up there:

best headphone amp.png

Noise performance is excellent as well:

SMSL SH-9 Measurements SNR.png

50 mv output which forces the output attenuation is good but not state of the art:

most quiet headphone amp.png

Frequency response is dead flat as we like to see:

SMSL SH-9 Measurements Frequency Response.png

Here is our power versus distortion starting at 300 ohm:

SMSL SH-9 Measurements power into 300 ohm.png

My threshold for desktop products here is 100 milliwatts and the SH-9 sails way past that to 226 milliwatts. So it should have no trouble driving high impedance headphones.

Switching to the other extreme at 33 ohm we get similarly excellent performance:

SMSL SH-9 Measurements power into 33 ohm.png

Using the XLR output with balanced load shows that there is no more output to be had:

SMSL SH-9 Measurements power into 50 ohm.png

As you see the drop THX amp in balanced mode can produce much more power. But SH-9 beats it in noise department and by good bit.

Finally, the key differentiation for SH-9: channel balance:

SMSL SH-9 Measurements channel balance.png

SMSL SH-9 Headphone Listening Test

I tested the SH-9 with my killer load: the Ether CX with its 25 ohm impedance and low efficiency. The SH-9 had no trouble whatsoever driving it with authority with no sign of distortion to any loudness level you wanted. Likewise it took the Sennheiser HD-650 headphone's neck and drove it to skull resonating levels with ease.


The SMSL SH-9 Joins other instrument grade, ultra-fidelity headphone camp. It mates nicely to its DAC sibling, the SMSL SU-9. It has an attractive, high contrast high resolution display with accurate digital volume control. The cost is also quite attractive. Misses are few which is lower power due to lack of balanced output, soft control buttons, and slow volume control.

I love differentiation without sacrificing performance which SMSL SH-9 brings. I am happy to put the SH-9 on my recommended list.