Hello,
I'm having some audio issues with Pillars of Eternity on Debian GNU/Linux. It seems that audio only works if I execute start.sh using sudo, which is a bit problematic...
All other GOG games I have are 32-bit and the audio works fine.

Does anyone have any ideas on fixes?

edit: It looks like I am having similar issues with Bastion on Steam. Audio only works on Bastion when run via sudo. Is there something in common between these two games? Perhaps Unity/Mono? All other games from Steam and GoG are working.

Both of those games use Mono for their Linux versions, yes. (Pillars via the Unity Engine; Bastion via the XNA/MonoGame framework.)

Looks like it's a problem with Mono. Just got Kerbal Space Program which also invokes mono and sound is not working unless I execute via sudo. My bet is that there is a permissions issue with mono, or all these games with separate mono folders are interfering with each other.

Problems seem to be related to an issue mentioned under github's valvesoftware steam-for-linux repo, issue #2968 (sorry not allowed to post links yet)
Purging pulseaudio got audio working again, for now.