adwaita-icon-theme.tcz not found!
Then download it. It is needed otherwise the icons in pavucontrol are empty boxs.
where is the pulseaudio control panel?
It will either be the icon in wbar if you are using wbar, or depending on your desktop, appear in your menu.
You need to set up pulseaudio as per its info file before attempting to use its control panel called pavucontrol.
You are not forced to use pulseaudio with vlc. You can use alsa or pulseaudio. vlc will normally detect either and attempt to use pulseaudio (I believe) if it can.
If you are using alsa with vlc.....and prefer not to use pulseaudio...you must have speaker-test working correctly.
If you are using vlc with pulseaudio.....as Juanito has said in the past, pulseaudio takes over the controls of alsa,
so you can not "pass" the speaker-test
The choice is yours. And it is acceptable that you set up one PC with alsa only and the other with pulseaudio.
Altho it the future it might have been better to start a new thread for each device.