Bug#808894: pulseaudio: No sound output to headphones even though headphones are detected and pavucontrol shows output.

[Jerad Simpson]

I ran into this issue with the version of pulseaudio in stable and
solved it last night, but my circumstances may be different, and are
unsupported by upstream.

Let me explain my fix and my use case, in order to seek advice here
and/or upstream.

Firstly, I use the unsupported system-instance, as can be seen in my
/etc/pulse/daemon.conf:

daemonize = yes
allow-module-loading = no
allow-exit = no
system-instance = yes

After some poking around, I appended the following two lines to
/etc/pulse/system.pa:

### Switch to headphones on connect
load-module module-switch-on-port-available

Follow this up with a 'sudo systemctl restart pulseaudio.service'

A lot of guides elsewhere will tell you that system-instance is
insecure, and should be avoided.  I use this anyway, because I could not
come up with a better solution for my use case.

I am the only user of my laptop, however, I do have have other users
that I 'su' to, and I want those users to be able to also play audio.
With the system-instance on, and the users in the 'pulse' group,
everything now works as expected.  With this post, I am soliciting
advice on how I can make this work with per-user sessions, because I
previously had no luck there.

Thanks,

Jerad