Howdy fhawk and welcome to the forum.Hope you enjoy you stay.
I'm not familiar with the MP1.5, however, about 40 years ago I did sound reinforcement for theatrical productions.
The house amps at the Candlelight Dinner Playhouse had similar adjustments for setting up the protection circuit.
I don't recall the brand and don't remember adjusting them though. (We didn't push them anywhere near their limits.)