I didn’t test this (and I do not have the problem you’re facing on any of my debian systems) but you could try to use mplayer instead of mpv: Arch Linux - Audio Not Working - #12 by Cassie.
I didn’t test this (and I do not have the problem you’re facing on any of my debian systems) but you could try to use mplayer instead of mpv: Arch Linux - Audio Not Working - #12 by Cassie.