This is an update to my
previous review of SMSL SU-8. At a retail price of USD $212 on Amazon and balanced outputs, the SU-8 could provide a very compelling proposition. Unfortunately the performance of the balanced output in my first review sample was disappointing, showing significant switching noise. SMSL was kind enough to send me a second unit recently and I put it to test.
There is no functionality difference so see the previous review for details of that. Briefly here, you get a nice looking unit with a tiny display and remote control:
[the 44.1 kHz on the display is not showing all the way due to my camera shutter not being in sync with its refresh rate.]
Let's get into measurements and see how she performs.
Measurements
Let's start with our unbalanced dashboard:
View attachment 18140
This is some 8 dB improvement in SINAD/distortion relative to original review sample! Let's see how our previously problematic balanced output performs:
View attachment 18134
Nice! As I show in the inset, SINAD used to be just 87 dB but now is a whopping 110 on average! This puts the unit in the upper echelon of DACs tested: [click on chart for larger size]
View attachment 18135
We can clearly see the reason in sweep of distortion versus frequency:
View attachment 18136
Good news translates into intermodulation distortion too:
View attachment 18137
There is no saturation as the levels go up to maximum as we had before.
Jitter was good before but we still see some improvements:
View attachment 18138
Low level linearity remains the same though:
View attachment 18139
Balanced (red) is near excellent. Unbalanced especially in one channel falls short though (still transparent though for CD rate music).
Conclusions
I must say, I did not have any expectation of improvements and I was pleasantly surprised. Looks like SMSL went on hunting for sources of distortion and noise and annihilated just about all of them! This is proof that better design can be had without any cost premium. The unit sells for even less now than it did then, yet its performance -- especially in balanced mode -- has massively improved. It has gone from "nearly broken" to "nearly state-of-the-art."
I am a big fan of balanced interconnects to break nasty ground loops that can be hard to deal with when you string a PC, DAC and amp together. If you look at the balanced dashboard and compare it to unbalance, you see complete absence of any mains leakage/tones. This is the power of balanced. With advent of high-performance balanced headphone amps like the
Massdrop THX AAA 789, there is even more of a requirement in my mind for balanced output DACs. And here we have one great option.
Needless to say,
I am happy to recommend the SMSL SU-8 for both its functionality and performance. Great to see them focus on performance clean up the design of previous version.
I understand there is a sale going on on Massdrop for a couple of days more. I would jump on it if you are in the market for such a DAC.