Hey Jack, The output mode in Touch 2's "Setup" menu only affects the analog outputs. USB audio output from the Touch 2 is just a wet stereo mix, and there's unfortunately no way to change this. If you'd like to separate the instrument and vocals in your recording, we typically recommend recording the instrument first on its own, then recording the vocals separately over that. It's likely you'll have to do some track-dragging in your DAW afterwards to line them up perfectly. Cheers!