Set your M80's and VP180 both to small and an 80hz crossover in your pre-amp settings and repeat those same conditions and volumes. You are taxing your amplifier at those volumes. This will take some stress off them. I'm curious to see if those amps will still shut down under those same conditions with these changes.

I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne