I'm assuming same as bjcsc... I would (A) check the radio's rear preouts for full-signal output(should be), then hit this up to a 3-way crossover("X"). Run the front/highs from the X to one channel on the amp for front speakers, run rears from the X to other channel on amp for rear speakers, then sub out to sub amp for the sub; -or- (B) pick up an EQ with seperate outs for front, rears, and sub. I'd go with (B), personally, but your mileage may vary.