To keep things as simple as possible, I think I should be able to tap the piano keys in the 'Pianos' tab of the mixer for the Thru track and see the Input VU meter respond and record the resulting audio somewhere. This somewhat dated video makes a point of demonstrating that: https://youtu.be/THKC6FvvrTw But since you asked, I'm using a re.corder by Artinoise as my midi controller. On Windows, one must install a 'bridge' application from Artinoise which then connects to a port provided by loopMIDI from Tobias Erichsen. This is like a virtual MIDI cable. BIAB connects to the other end.