To GPO4 and 16 (?) tracks for the audio outputs from GPO4. (f) select > 'Build 16 channel of MIDI routing to this track'Now you will have 16 tracks sending MIDI (on channels 01. (e) open the FX window for the GPO4 track (click the button) (d) click on the 'Build Routing confirmation' window that will create tracks for all of the audio outputs from GPO4, (b) select 'Insert virtual instrument on new track' Try this set-up: (a) right-click in the TCP area below any existing tracks If so, then yes you can do that too in Reaper.
Hmm, from what you have said about Sonar I can only think that the ARIA Player DOES respond to CC#07 for volume and CC#10 for Pan.