I ran into and resolved a problem with getting audio working in RetroPie on the Picade Max, and I figured I’d share here.
The instructions in the setup docs didn’t work for me; it refers you to the Recalbox section for setting up audio, but the settings menu in the RetroPie build don’t seem to match what’s in the Recalbox screenshots, and I couldn’t figure out the right settings. (Configuring audio in Linux is a pain. Go figure!)
What ultimately worked for me is, from a clean Pi OS Lite installation, I edited the firmware config (i.e., sudo nano /boot/firmware/config.txt). and changed the line
dtoverlay=vc4-kms-v3d
to read
dtoverlay=vc4-kms-v3d,noaudio
This disables the HDMI audio output at the firmware level, leaving the USB audio card to be selected as the default. Then in the RetroPie audio settings, I was able to change the source selection to HW and PCM, which got everything working: Games have sound, and the hardware volume knob works.
There might be a more principled solution, and I’d be happy to hear it, but it was a bit of a struggle getting this going, so I thought I’d share this solution here in case other people hit the same issue.
gl, hf!