So it appears to be a kernel issue. Ultimately I’ve installed the linux-lts510 kernel on Endeavour for the time being. I’m going to mark this as solved, as the amount of people still running this audio interface is probably relatively small, and even less using Linux. I suppose I’ll probably look into getting a new audio interface in the future, but for now this works.
For anybody else who runs into this issue, or similar:
I added this to the end of /etc/pacman.conf
[kernel-lts]
Server = https://repo.m2x.dev/current/$repo/$arch
and then from this page https://wiki.archlinux.org/title/Unofficial_user_repositories#kernel-lts got the key to then import and sign
sudo pacman-key --recv-keys 76C6E477042BFE985CC220BD9C08A255442FAFF0
sudo pacman-key --finger 76C6E477042BFE985CC220BD9C08A255442FAFF0
sudo pacman-key --lsign-key 76C6E477042BFE985CC220BD9C08A255442FAFF0
and then updated my system
yay
after which, I ran
yay linux-lts510
and then rebooted.