Driver for CM6631A USB chip (c-media)

Hello, I wonder if there is a driver for this usb chip that can be installed on ropieee? My dac is not seen as it is now. The usb dac chip is CM6631A. The dac is Hegel HD25.


That’s not how it works on Linux. There is no need for a specific driver.
Can you send me feedback (with the DAC connected and powered on) so I can see why it is not being recognized?


Thank you for the response. How do I look for the information on what you need? Is it in the ropieee web interface page when I log on that ip adress?

Go to the ‘advanced’ tab of RoPieee’s webpage and hit the ‘send feedback’ button.

Ok, thanks. Feedback sent.


2 things:

  • you’re running an old version. please update RoPieee.
  • there are reports about a possible bad cable.

So I would suggest you first update and then try out a different cable.


Thanks! Yes I will update, thanks for the information.

About the cable, it works with other dacs I have, so that’s very strange… There’s a switch on the back of the Hegel HD25 which switches between 96 kHz and 192 kHz. Can this be involved with this?

I can also say that I had the same problem with my previous dac, also a Hegel, Hegel HD12. Both use the same USB chip, the c-media CM6631A.

It has nothing to do with the chip, but the implementation (on the Hegel side).
Have you tried the switch on the back of the Hegel?

Yes, I have tried to flip the switch. Nothing helps. I guess Hegel have done something that Linux doesn’t understand then.

They probably did not test on Linux. Are they claiming they support UAC (USB Audio Class)?
Isn’t there a firmware update available?

I’ve read the manual. I think you definitely need to select mode “B”.
What I’ve also read that you need to to this with the DAC disconnected.

Have you done that?

Yes I’ve tried both a and b with the cable disconnected. There is no update avaliable on the Hegel.

Hegel claim to support USB audio class. They also told me in a mail that the dac supports Linux. They suspect there is some kind of compatibility problem involved.

Thanks a lot for your help!

Can you send me feedback with the DAC on setting ‘B’?



ok, but you still did not update. I’m interested in an up-to-date feedback.

I thought I was, don’t know what happened really. Anyway, updating now. Will reply with feedback when it’s done!

Here’s the feedback on updated version. Thanks!


Any hope for a solution? Is Hegels usb implementation difficult to work out?

I used to have an H360, and I think I recall some issues with USB from Linux back then, and a specific document on Hegel’s site about this. However, I could not find it searching now, although there’s a mention of that document in the PDF manual for the HD20. I used the H360 with an external DAC so this wasn’t much of an issue for me.