You might use the Advanced Scene Switcher to do that:
W
Can automate various tasks
If the Audio Monitor can accept a hotkey, that appears in OBS's list to assign, then Adv. SS can send that hotkey directly, without having to actually assign it. That gets you cross-plugin automation, without the risk of fat-fingering something.
Adv. SS then, receives the MIDI command and sends the hotkey...in addition to a LOT of other capabilities! It can see and do almost anything inside of OBS proper, plus a few things in the outside world.
