Guidance for Volume to IP plugin

I wish to write a plugin that
“steals” the VolumeUp/Down/Mute “signals”

I wish to be able to do this, so that I can
forward the Volume(s) directly to an a/v receiver

In my case the receiver is a NAD talking commands
over telnet

E.g. using the volume key on the “android kodi remote” will send
keypress (I guess) to Kodi. I would like to have those presses
not handled at all by kodi audio engine, but forwarded to my
add-on and on to the IP network. I want zero volume
handling by kodi (I use passthrough)

Searching the kodi-git I fail to find a suitable entry point
for my code.

Any guidance highly appreciated