I’ve looked at suggestions on StackExchange and made some changes to files in /etc but after each login or reboot it is up to 100 % again in pavucontrol. On this computer I hardly ever use the speakers, and I want the microphone muted, always, so I guess I could even block list a few kernel modules for sound (which ones ?). But why can a desktop user not easily turn volume to zero, forever ?
Sure. The solution was already in the edit part in the post. The solution that worked for me was to switch to Dummy in Pavucontrol.
Thank you, when I last viewed it, the title was changed to solved, but I did not see the edit. Cheers!