Re: Not exactly what I expected from Crutchfield
I just put the exact same HU in my car - looks and sounds great. I was bummed about the non-vehicle specific install guide but it was not too difficult to figure out.
The 4 RCA plugs were correctly attached to the wire harness so you could hook up directly the the HU Pre-Amp outputs giving you a cleaner sound that is why Crutchfield website told you you would be able to use the factory amp and bypass the amp built into the HU and actually went the extra step to hook up the RCA plugs for you. (On HUs with less than 4Volts Pre-Amp it would not work well but this HU has the neede 4Volts).
Obviously the front speakers go to the front speakers but I could not decide whether to use the sub-woofer pre-amp outputs or the rear speaker pre-amp outputs for the rear speakers. Tried both thought using the sub woofer outputs sounded a little better so hooked it up that way.
The HU has tons of adjustments to dial in the sound exactly as you like it - or if you are like me drive you crazy trying to decide which sounds best.