SMSL SU-8: The Little DAC That Couldn’t

 

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This is not a review. This barely even constitutes as first impressions, but there are some things I need to say about SMSL‘s new standalone digital-to-analog converter, the SU-8. I’ve been really excited about this product because it looks like a Swiss army knife of a standalone DAC with a very small footprint and a clean, minimalist aesthetic. I knew it would be compact, but, when I unboxed it, it was even more compact than I had ever imagined. At the same time, the SU-8 has a nice weight to it and the finish is excellent. I wanted to love this $200 DAC so badly.

 

Wanted to, but couldn’t. When I plugged in the SU-8, I was immediately assaulted with so much electrical noise I thought the unit might be faulty. I’ve since spent hours experimenting. I’m not sure how I did it, but I managed to drastically reduce the amount of noise coming from the unit. Plugged into a more forgiving headphone amplifier like the HeadAmp Gilmore Lite Mk2, it sounded excellent, but the problems returned when plugged into higher output impedance amplifiers like the Beyerdynamic A20 or the Schiit Valhalla 2.

 

I’ve narrowed it down to the USB input of the SU-8. There’s a reason companies like Schiit have gone through multiple revisions of their USB implementations: USB is problematic for audio. Admittedly, you have to crank the volume pretty high and not have any audio playing to hear the noise, but, when you do this, it is very present and causes one to question the quality of the DAC as a whole. I put the Schiit Gungnir Multibit and the Schiit Bifrost Multibit, both much more expensive DACs with Schiit’s latest Gen 5 USB, through the same tests and there was no hint of noise that wasn’t coming from the amplifier itself.

 

 

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I’ve actually run into this before. When I plugged the line out from the integrated audio on an ASUS Z170I Pro Gaming, a rather mediocre motherboard, into the Beyerdynamic A20, it was nearly vomit inducing. That’s the thing about the A20: It exposes the flaws in any source. If your incoming signal isn’t absolutely flawless, the A20 is going to let you know about it. The Valhalla 2 isn’t quite as sensitive, but it confirmed my suspicions when I realized that the biggest cause of the electrical noise was my mouse movements. Any time I moved my mouse, I was getting audio feedback. This was confirmed on more than one computer, both equipped with a Cooler Master Storm Spawn optical mouse but different motherboards from the same manufacturer: the ASUS Crosshair VII Hero and the ASUS X99-M WS. These are both very high-end motherboards, the latter being a workstation-class motherboard and the former the most premium motherboard you can presently buy for the X470 platform.

 

With music playing, a more forgiving amplifier, and volumes kept at low to medium, the SU-8 might be indistinguishable from either of my standalone Schiit DACs, but it’s pretty clear that corners were cut somewhere and I believe that somewhere is the SU-8’s USB implementation. It shouldn’t be picking up electromagnetic interference from my mouse movements or anything else. No other DAC ever has. Even the JDS Labs Element, which suffered from terrible EMI issues from cellular activity, didn’t pick up my mouse movements and I suspect it was the amp section of the Element that was problematic rather than its DAC section.

 

Bear in mind that the Cooler Master Storm Spawn’s fixed cable comes with a ferrite choke just before the USB termination point. In an attempt to remedy the issue, I substituted the SU-8’s stock USB cable for a Tripp Lite U023-006, a high quality double-shielded USB cable with dual ferrite chokes on either end. It made no difference whatsoever. A Schiit Eitr would probably fix the SU-8, if not a Schiit Wyrd, but I don’t feel particularly inclined to spend $100-$180 to “fix” a DAC that shouldn’t need fixing.

 

Due to these issues, I’m not even going to bother reviewing the SU-8. I recommend others avoid this purchase.

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