How come when i turn my pre-amp <think> it kills the 6x9's and front door speakers. Thought if it was ON then it would help them out a little bit. This one has got me stumped. is it hooked up wrong?
It means you've disabled the built in amplifier that powers the speaker wire outputs. It does that so the unit doesn't heat up as fast and in effect causes less distortion to the RCA pre-outs. The only reason to have it ON is if you are running your system only through the pre-outs.