S.M.S.L SH-6 Amp: Closer Examination

I deliberately took similar photos of the SMSL SH-6 amplifier as with the SMSL SU-6 DAC on the previous page, to showcase how similar they are overall. This is on purpose to allow the two to effectively stack together, encouraging customers to purchase both and use them together. As with the SU-6, the SMSL SH-6 comes in the same two color options for the outer shell, with an anodized finish to the aluminium chassis. I again have the black version, making for a matching stack. The SH-6 is slightly larger than the SU-6 coming in at 140 x 115 x 28 mm and weighs more at 380 g too but this difference isn't big enough to make any practical difference once set up. The Hi-Res Audio badge makes another showing here on the top, and we see the front foregoing a display as expected. This is an entry-class headphone amplifier with a single 1/4" (6.35 mm) output and comes with branding on the left alongside a tiny power indicator LED. Then there are two physical switches, with the first allowing you to choose between the output functionality of the unit (off/preamp/headphone amp) and the second going from low (0 dB) to high gain (15.5 dB) modes. To the right of the headphone output is the expected volume knob, getting a knurled finish for better grip and an indent on the top to help indicate the active position.


Given the SH-6 was designed to be used with the SU-6 DAC, it's no surprise to see only a single-ended input in the form of the same RCA connectors on the back. These come marked clearly to help distinguish them from the RCA outputs to the right, which in turn are handy as a pass-through for when you want to connect the SH-6 to a set of powered speakers and use the SU-6/SH-6 stack as a preamp. The "PRE" option has to be selected on the first switch on the front for this. Then we see the grounding pin next to the 2-prong power input itself and another switch to turn the unit on/off accordingly. Once again it would have been nice to see dust protective covers for the unused RCA connectors.


As with the SU-6, we see four small hemispherical rubber pads on the bottom to raise the SMSL SH-6 amp. These do double duty by also providing some room for passive heat dissipation, when using the two as a stack one above the other. Disassembly is similar and equally futile, in that you get to the same point following which you can't proceed without desoldering, but here too we see a separate low noise power supply inside which is almost never the case in the price range the SH-6 operates in. You typically get a bulky power adapter with built-in transformer or, worse, a 2-piece external power supply + cable. SMSL boasts the power supply's output noise is lower than anything perceived, with the value essentially being masked by the noise floor of the excellent Audio Precision APx555B analyzer the company uses and provides measurement data for its products from. The SH-6 is otherwise a straightforward linear amplifier with a rated THD of 0.00006% at <-125 dB and SNR of 134 dB to where people should not be concerned about the quality of the output power itself. The ultra-low output impedance of "near 0 Ω" for the headphone output makes this suitable for just about anything plugged into it, whereas the preamp output impedance is a respectable 22 kΩ.