OK, that's going to cause some serious head-scratching.

Without going near the "better sound" part of it, I don't think I even have an explanation for why you were able to turn the volume up higher before the amp shut down.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8