As opposed to not amping speakers in the rear doors? If you have both, you should amp them. If you are just flat broke HU power will work but you run the risk of clipping the HU at high volumes to the rears while the fronts play fine. Easy way to destroy the rears. The easiest solution would to not have any rear spears....besides a sub that is. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif