THE BAD NEWS: Tonight's stream had to be canceled due to audio glitches with OBS.
THE GOOD (and stupid) NEWS: I figured out what the problem was, and it's so dumb and was so easily avoidable I want to kill myself.
My Roland VT, which acts as the audio hardware between the mic and the streaming PC, is plugged into USB on my daily driver/browsing PC for power. The daily driver PC picks it up as an audio device, but I can go into Settings and disable it, which I always do.
For some reason, this time I thought I had done that, but did not. As such, the daily driver PC was treating the VT as an audio output device. I also had my PeerTube instance front page open in a background browser tab on the daily driver, and the embedded PeerTube livestream autoplays when it starts.
So every time I streamed, the daily driver PC would play the stream audio, output it to the Roland VT, which would pass it through the Line In on the stream PC and add it over the mic audio.
Literally all I had to do was either a) disable the VT as an audio device like I always do, or b) /close the fucking PeerTube tab/ and everything would have been fine.
I wasted four fucking hours of going through every setting imaginable and combing over OBS forums for nothing 😡
I look forward to Streaming Saturday every week for the whole week, and to squander it completely for something so utterly stupid and avoidable, I want to fucking neck myself, fuck