"Part 4 ARDUINO MIDI CC TO SYSEX YAMAHA QY70 CONTROLLER KEYBOARD AXIOM PRO 61 EVENT PROCESSOR"
Sorry about the bold - cant seem to turn it off. Above is the title of a Utube video uploaded by Tech Tinkering. Very interesting in general, but a short quote from the intro:-
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"The track mixer on the qy70 is notorious for being awkward to mute/unmute"