Set default system audio output port (for all accounts)

Question

The default output audio port Ubuntu doesn't work on my system. It should be "Analog Mono Output/Amplifier", instead of "Analog Output/Amplifier". I can easily change that in sound preferences, just by choosing the right port in the "Output" tab. The problem is this would only apply to a single account, and I would like to change it system-wide, so it applies to all accounts on the system (I have more than 100 users...).

I'm after 2 hours of Googling, so any help would be appreciated.

Update: I can achieve the same effect as I would by changing it in sound preferences using the following command:

pacmd 'set-sink-port' 'alsa_output.pci-0000_00_1f.5.analog-stereo analog-output-mono;output-amplifier-on'

Unfortunately that's still not system-wide, so doesn't help me much...

Answer 1

I guess you need to set default-sink in pulse-client.conf, see man pulse-client.conf but I didn't test that.

Answer 2

I've got he answer, thanks to Ford_Perfect in #pulseaudio IRC channel.

I needed to add the following line to /etc/pulse/default.pa:

set-sink-port alsa_output.pci-0000_00_1f.5.analog-stereo analog-output-mono;output-amplifier-on

This solved the problem, but for some mysterious reason also made sound muted by default, and set default volume level at a very low. So as a workaround I added the following lines to the same file:

set-sink-mute alsa_output.pci-0000_00_1f.5.analog-stereo False
set-sink-volume alsa_output.pci-0000_00_1f.5.analog-stereo 30000

One more important piece of information: to use the above instructions you need your sink name (in my case alsa_output.pci-0000_00_1f.5.analog-stereo) and name of your sink's ports (in my case I used analog-output-mono;output-amplifier-on). You can get them running pacmd list-sinks command - it will list all your avialiable sinks, together with their ports.