I pulled my Pioneer HU out a couple of months ago and installed the factory head unit. Reason being I was planning on getting rid of all of my car stereo stuff. I decided to keep it and plugged the Pioneer HU back in. Now the unit gets power and turns on fine. The problem is when I turn on the HU I just hear a pop out of the front passenger side speaker, but that all. Absolutely no sound from music. All I hear is that one pop. I removed all of my amps and have put the car back to the factory sound system. The only custom thing is the HU. Does this sound like the eternal amp in the HU is blown? I checked the back of the HU and the little fuse is not blown. When I plug the factory unit back in everything is fine.