I hooked up an Alpine amp for 2 - 10" JLs, and an old school Earthquake 4 channel for some MTX 6x9s and MTX 5.25". I tapped into the factory Bose amp harness under the dash to feed my high/low converter that feeds a 7 band Clarion EQ, Audio Control Epicenter and then my bass amp, from the EQ I also sent the front & rear RCAs for my highs... from the EQ I can adjust my bass level, bass frequency, master volume, front & rear fade, & of course the 7 EQ bands. It even has an auxiliary input to hookup another music source. The EQ really makes the stock head unit sound good.
It sounds like a lot of equipment for a stock deck but I really want to keep my stock deck for the sake of not getting my car broken into. By looking through the window you can not tell that my car has any music in it.