Pirate Audio amp alsamixer: no controls

I am trying to use the Pirate Audio 3W amplifier to play audio files, not using mopidy, but aplay or cvlc.

However, I seem to run into an issue that I can’t figure out how to solve. When I run alsamixer it says “This sound device does not have any controls.”. Any idea how I can get around that?

I already tried looking into /etc/asound.conf, but I’m a bit unsure what should be in that file for the volume control to work.