I recently re-worked my sound system and by-passed the factory system. I installed a Nakamichi CD player in the DIN opening where the CD player is and modified the trim from the non-working player to cover the gap. The Nak head unit powers all speakers in the car except for the Infinity Basslink. All speakers have custom crossovers to keep the impedance a 4ohms - pretty much like how home speaker crossovers work. Here are the notes I took for wiring and amp locations.