Regarding the blip, I suspect the blip is because the audio route from your rack to your hardware output is also being disconnected and re-established in the new song. Again, you can probably work around this by sending directly to the hardware audio port inside your piano rack, instead of going to Rack Stereo Out (or whatever your rack calls it).
Obviously this isn’t desirable for the same reasons as accessing the hardware MIDI port directly inside the rack, and it also means you can’t do any song-level processing or even level adjustment. 