I don't know much about amps, what I have learned I have learned from tanstaafl. I have a a/d/s P850 which has 8 channels. 1&2 run my dash speakers, 3&4 run the doors, 5&6 run the rears and 7&8 run my one 10" sub. I like being able to tweak each set of speakers individually. I'm not sure about the power question but you would have more tweaking options running the subs off their own amp. I have the Diamond S400S in my dash and they are incredible on the highs. So your car must sound pretty damn good.