[mikegett]

The infinity reference is a very nice coaxial. They always had a good natural sound to the highs opposed to being overbearing or weak. Your stock speakers can't handle the higher wattage but are more sensitive. Meaning that they will sound louder and cleaner with your HU power at near full volume. Running your coaxial off the HU will result in a speaker requiring more wattage than the HU can provide. This means that in order to get the same volume you will need to increase the HU past the volume range of your OEM speakers. Unfortunately, this will max out the HU and result in clipping. You have a few options. The front speakers can be amped while your infinity is left on the HU. Since rear is more for mid bass and slight fill, you can set the front gains to max out at 3/4 volume and prevent your rears from reaching clipping. Or you could place a small amp on your rear fill only. In this case, I would suggest crossing it over for low pass only and use the infinity for midbass. Otherwise, you could amp all four channels. This is my own preferance. Even your facotry speakers will sound better with more wattage.