Clicks/pops on Reference DAC using ProUSB/AOC

Support
1

Hi!

I’m hearing frequent glitches / clicks when using the ProUSB module on my Reference DAC. When connecting via Coaxial/AES the issue is completely gone. The setup I am using is as follows:

ASUS NUC w/ Win 11 (used as Roon server) → USB cable (USB 2.0 port) → MSB ProUSB → AOC cable → Reference DAC

I have updated / reinstalled all the latest firmware & drivers as well as rebooting all devices multiple times to no success. I have tried various buffer settings in the MSB USB driver settings, the higher buffer settings seem slightly better but don’t solve the problem. I have tried different USB cables and USB ports in the NUC.

The issue became noticeable when after I switched to a longer AOC cable (exact same spec / brand as previous one) - but I’m not 100% sure as the clicks could’ve been there before without me noticing as I’ve only been using the ProUSB setup for a short amount of time.

Any idea what the issue could be please? In the meanwhile I am listening via Coaxial (with a clock sync cable) - the sound is amazing either way but I do think the ProUSB offers slightly more resolution.

Thanks a lot in advance for the help!

2

Hello Ratou,

What length AOC did you have? What length did you go to? What brand? If you go back to the original length AOC does the problem go away?

3

I went from 10 feet to 16 feet using the recommended AOC cables found on the MSB support page:

I will try the previous cable and let you know. Is the AOC cable directional? Both connectors looked identical so I assumed it was not directional.

4

2 m Generic is correct. The difference between 10ft and 16 ft is nothing. We have people using them at 35 ft and more. AOC should be good for hundreds of feet with no losses.

Let me know if going back to the shorter length correct, the problem. If so, I think it is not the length. Maybe the 16 foot version was damaged somehow. If the single fiber cable going into the SFP module gets tugged at all, there is a concern.

Best Regards,

Vince Galbo
MSB Technology
National Sales Manager
716-688-3527

5

Thanks for your help.

The issue is the same with both cables sadly - so I guess it rules out any issue with the AOC cables themselves?

The NUC has received some automatic Windows updates recently (I dont know if that coincides exactly with the time I started noticing the clicks/pops) - could that be causing the issues?

6

I’ve also tried swapping back to the regular SFP + cable modules and the issue is the exact same.

7

Any suggestions / troubleshooting I can do please? Could it be a hardware issue? The Pro USB adapter I’m using looks like its the older model with the “ears” that stick out on each side.

8

On your ProUSB module, do you see a V2 sticker on it? We are constantly trying to minimize these ticks/pops with the ProUSB and servers. You can also try enabling the “resync” delay in Roon and see if that does the trick. What’s happening is some servers/software will feed a small amount of digital trash into the data stream when changing sample rates.

The V2 version of the ProUSB is a little better at helping solve this issue. The audio quality between V1 and V2 is the same; it’s just an attempt to reduce this noise from some servers.

9

Thanks for your reply.

I have already added a 500ms “resync” delay and use the maximum buffer size on the MSB ASIO driver. It helped with ticks during song changes but didn’t fix the ones that occur during playback (in the middle of songs).

The ProUSB module I have doesn’t have a V2 sticker on it so guess it’s an older version?