tetris11 , 7 hours ago (edited 5 hours ago)

Pulseaudio should have hooks

<span style="color:#323232;"># cat /etc/pulse/default.pa
</span><span style="color:#323232;">load-module module-switch-on-connect
</span><span style="color:#323232;">load-module module-exec
</span><span style="color:#323232;">load-module module-exec arguments="path/to/your/script.sh %s"    
</span>

(where %s resolves on trigger to the name of the sink added)

Your script.sh should then match the first argument to the name of the sink you want to control, and then run

<span style="color:#323232;"># path/to/your/script.sh
</span><span style="color:#323232;">if [ "$1" = "THESINKIWANT" ]; then
</span><span style="color:#323232;">  pactl set-sink-volume $1 40%
</span><span style="color:#323232;">fi
</span>