he must only be using the amp to power either the front or the rear speakers only - not all four with a single 2 channel amp. if you want to amplify both the front and rear and be able to fade from front to rear (and why would'nt you?)... why yes you do need two two channels!!! if you are going to be using front and rear speakers you will need to be able to control the relative levels of the front and rear speakers. like with a 4 channel or two 2 channels. if you are going to just use one 2 channel then amplify the front only and let the HU power the rears.Originally posted by Eclipse18 you dont need two two-channels, we used one two channel in my buddys car but i wanted to know if there would be a difference in sound quality or anything else....