It turned out my speakers are bad, on low volume it becomes distorted. Mid level volumes are OK but not sounding right. The worst one is on the rear passenger door. Replaced the front ones with new Pioneer 3 way speakers and shifted the fader to Front only, big improvement. Going to swap the old front speakers with the rears this weekend. I also replaced the HU with a bluetooth capable one, I could make and receive calls without taking out my cell from my pocket as well as Pandora and music streaming.