That’s not a feature we have right now.
The master track is a bit of a pseudo track in that it really just holds master plugins and these get applied to the “default audio output” device. So any tracks that output to the default device will get the master plugins applied.
They’re not really routed to or through the master track.
Improving this so it is a proper routing destination is something I’d like to do one day though.
You can do it like that. Just note that your masterTrack there has to be an AudioTrack. The te::MasterTrack can’t be a destination as it doesn’t have a true audio path.