I'm running Devuan GNU/Linux Beowulf. For various reasons, I've manually downloaded and installed a newer version of Firefox 76 (from here) and installed it under /opt
.
This works fine. However, when I play media using the browser - say, a YouTube video or just any simple mp3 file) - I don't hear any audio. My distribution-supplied Firefox install plays audio just fine.
There don't seem to be any audio-related settings in Edit|Preferences, so I'm not sure where to look and what settings I need to fix this.