Originally Posted by MMZ_TimeLord
The factory amp should not even work half way with pre-outs. You should only use speaker outputs to power the factory amp, just as the factory head unit does.
Cheers!
Mine is hooked up as described by the OP
HU front preout to L/R input on amp
HU sub preout to L/R sub inputs on amp
Only difference is his pioneer pumps more voltage out of the preamp than my alpine if I am not mistaken. I hooked it up like factory before I switched to preouts and volume was way higher but clarity at high volumes was garbage like stock as the speakers just can't handle it. Also couldn't control fronts/subs independently.
How did you do your setup? Just bypassed the factory harness straight to the amp using the regular L/R front wires coming out of the HU?