Received my Series 3 today. Evey month or so, I play with a different band on a big hollow stage, with backline provided. It's a Peavey Mark somethng or other, with a 1x18 and 2x10 cabinet (one cabinet). It sounds terrible. It's boomy and some of the higher notes just disappear. I've already played with the amp's controls, tried two different compressors, Sansamp Para Driver, Sansamp BDDI and Carl Martin Para EQ. It still sounds like sh!t; lows boomy, highs disappear. I'm hoping the HPF will help... with the boom anyway.