What makes you feel like you are pushing the cab to it's limits? If you want it a little louder, just turn up. Don't get too hung up on the red indicator light for your input gain. That's just how Ampegs are. Some folks get their grit and distortion by cranking the input all the way up so it's red all the time. Highly doubtful you'll blow that cab with the PF, but if you can't get the volume you may need to tweak your knobs. I'm a knob tweaker myself and end up setting most of my Ampegs pretty much the same, but start with the ultra lo and ultra hi off, set the EQ to noon, and then set your gain and volume. Tweak your EQ/tone from there.