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SMSL SU-8 Version 2 Balanced DAC

amirm

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#1
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:
SMSL SU-8 DAC Version 2 Review.jpg

[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:
SMSL SU-8 DAC Version 2 Unbalanced Measurement.png


This is some 8 dB improvement in SINAD/distortion relative to original review sample! Let's see how our previously problematic balanced output performs:
SMSL SU-8 DAC Version 2 balanced Measurement.png


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]
SMSL SU-8 DAC Version 2 SINAD measurement.png



We can clearly see the reason in sweep of distortion versus frequency:

SMSL SU-8 DAC Version 2 THD vs Frequency Measurement.png


Good news translates into intermodulation distortion too:
SMSL SU-8 DAC Version 2 IMD Measurement.png


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:

SMSL SU-8 DAC Version 2 Unbalanced jitter Measurement.png


Low level linearity remains the same though:
SMSL SU-8 DAC Version 2 Linearity Measurement.png


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.
 
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#4
Do you have any concern that there might be quality control issues? You were able to catch the issue because you have the gear and know how but the person that had drop shipped that to you probably doesn't and would never have known they had gotten a faulty unit. I realize this can happen with anything you buy but it does make you stop and question it when it sells for so cheap.
 

amirm

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#8
There was a request for a properly labeled response of reconstruction filter in the other thread so here they are:

SMSL SU-8 DAC Version 2 Filter Response 1 through 4 Measurement.png


SMSL SU-8 DAC Version 2 Filter Response 5 through 7 Measurement.png
 

maxxevv

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#10
Great to see SMSL taking the performance of their products so seriously!
Hope this sets a precedent for other manufacturers to follow with regards to fixing " broken" performance products.
 

amirm

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#12
OK, I took it apart and here is a quick picture. Higher fidelity ones will come later:

SMSL SU-8 DAC Version 2 Main PCB.jpg


I have circled the revision on the left: September 27th, 2018, version 1.2.
 
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#13
I have circled the revision on the left: September 27th, 2018, version 1.2.
Wow, that seems hot off the presses! Do you have the original board still? If so any chance you can show what revision that one was?

I can't seem to find how old this dac is but it's potentially 6ish months old. So I would guess it's a dice roll as to which revision you will get. However if SMSL will send replacements if you get an older one then perhaps there isn't much to worry about?
 

amirm

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#14
Wow, that seems hot off the presses! Do you have the original board still?
No, that was a loaned unit that was sold so I never opened it. Since it was purchased before this revision, it must have been different.
 

maxxevv

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#17
How is making fixes after release "taking performance seriously"?
I was referring to fixing 'broken' products.

As you know very well the story of that other brand that keeps making denials and excuses for its broken products not measuring well .....
 
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#20
I bought my SU-8 on July 14 this year, around the time @amirm post his first report. I just take a liberty to open up the unit and take some photos of the board.
IMG_5144 small.jpg
IMG_5145.JPG
IMG_5146.JPG


Notice that the version number on the lower-left corner of the board. It is version 1.0, dated on April 13, 2018.

I cannot really hear any flaw on the balanced output, personally. It sounds very good since day 1, and work till today flawlessly. Nonetheless, I am more than glad to see SMSL has made continuous improvements on their product.

Thank you so much @amirm! Thank you to all members in this community.
 

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