Is it possible to control the track mixer externally? I couldn’t find CC numbers for these in the manual. Or, perhaps, I should just use CC 7 for the volume from the Amp page for each track individually (and map it to different knobs of my controller)?
Is there a better/more convenient way of doing that?
The master page mixer is just a different view of the Track Level values of the audio tracks, so you should just use CC message 7 on the MIDI channels that you have assigned to the audio tracks.