On Tue, 16 Jul 2019 08:06:20 +0100
Philip Ashmore <contact@...> wrote:

> Sometimes the sound starts muted and I have to enable it with kmixer 
> which tells me that I have two mixers, PulseAudio and "HDA Intel PCH".
> 
> Maybe that's because I end the session with earphones plugged in and 
> start it with them unplugged, not sure.

"HDA Intel PCH" is the underlying ALSA mixer and PulseAudio is layered on overtop.  
ALSA is the real sound system--Pulse just offers some auxiliary services like easier
Bluetooth association, and you may not need it at all if your sound system only involves
local wired speakers and/or headphones.  (Early versions of PulseAudio were also
notoriously buggy, but hopefully you're not running a really old version.)

The automute could be coming from a conflict between the two layers, or from ALSA
being unable to save settings on system shutdown for some reason.

E. Liddell