Due to a recent video card purchase, I've had to switch to -current (newer Mesa, X11, & LLVM). It turns out, I also need to use a 4.20 or 5.0 series kernel, or the amdgpu driver won't load at all.

The problem is, ever since switching to -current, I'm getting some USB audio glitches. Like the sound gets garbled momentarily every few minutes or so. The most visible complaint is Firefox emitting this:
...snip...
The glitch happens in any multimedia player, not just Firefox. Actually, the stock huge kernel is sort of usable (other than X running on the VESA driver, lol), and the issue gets much worse with a kernel switch. I compile the newer kernels with the config-generic from /boot, and select defaults on all new options.

I've tried the pure-alsa-system mod, but ALSA won't even try to output audio through a (class compliant) USB interface for some reason. So I can't even confirm if this is Pulseaudio related or not.

Any suggestions are welcome.

EDIT: Were the stock kernels compiled with GCC 9.1? I'm getting a large number of compile warnings during the kernel build. I wonder if the new GCC might be causing some subtle breakage.

Ok, so removing some extraneous USB devices seems to have solved the issue for now. Interestingly, this never happened with Slackware 14.2 with a 4.19 kernel. I guess something changed regarding USB handling in either the kernel, or slackware64-current.

Anyways, marking this as solved.