What to do with a bass amp that overdrives itself when turned too loud?

I recently discovered that during band practice when I turn my Peavy
max 112 that if I turn it up to like a 5 and above, or when i turn my
effects pedal up or i turn my bass up it's starts overdriving itself.
What cab I do to prevent it, also could it also be my new effects
pedal- its a Boss ME50B. I'm currently using the effects loop to go
from my amp to my pedal and back, I used to go from my bass to my
pedal to my amp but still had the same problem. Cause I have never
encountered this problem before, also my friend said that it's because
the room is very condensed and crowded. I also never encountered this
problem when I'm playing in my house or my other friends garage which
is quite spacey. And I have tied different variations of turn my bass
up and amp down or turn amp up and bass down or effects pedal up and
amp down or pedal down and amp up but in the end it always ends up
overdriving itself.