Sadly (and gladly), I have duplicated the problem.
I have been "stress testing" Teensy 4.1 units in a female-header-mounted manner (on my customer daughterboard) before soldering them in without the headers. All have run without trouble for at...
I think I see it all in usb_desc.c.
I've tried some permutations and so far I either enable or disable both input and output.
My test for success it's a zoom session bringing up the audio input and output menu. My device appears in both audio...
@Jigglypuff were you able to create a USB audio interface that is recognized only as a microphone (input), and not as a speaker (output)?
And if so, what is the minimal change to do so?
I've looked at usb_audio.h and find this class declared...