speaker distortion

I just completed my first install. New cd head unit, rear deck, and front components, no amp. It sounds good, but when playing loud, I will get distortion after about ten minutes. I try to isolate it using balance and fader, when separated there is no distortion when playing only the rear...

Alright so yesterday I bought and installed some new speakers for my Chrysler 200 (2013). The car has a 6 speaker setup with four 6x9's in the front doors and rear deck (I got Infinity Reference 9633cf's) and two 3.5"s (Polk DB351's) in the dash. I've had an aftermarket head unit for a bit now...