No sound from USB Audio Interface

Hi, I’ve been trying to get a new install of Patchbox OS and Modep going on a RPi4 with a Behringer UMC204HD USB audio interface. In the initial setup I selected the USB interface. However I don’t get sound out.

To see what is working, I setup an effect chain in Modep from the audio input to the output of the interface. To see whether there are any signals coming in and going out I added the frequency analyzer plugin. Both indicate there’s a signal going in and out of Modep, but I don’t hear anything from the Modep output connected to the amp. I do hear the signal that goes directly from the input to the output inside the hardware.

I’ve searched the net to find anything about ALSA, Jack, Patchage, etc. but I haven’t found anything that brings me closer to a working setup. Does anyone have any source of information that could help me understand what’s going on?

Thank you for your help.

There may be some helpful suggestions here:

Aside from those, does it do the same thing from the USB 3.0 ports & the USB 2.0 ports? I ask because I had a Lexicon that would not work on the 3.0 ports.

Check the ALSA mixer controls (alsamixer), sometimes it must be reconfigured in order to get any sound.