Thread: strange noise coming from HU (sounds like I can hear the CD spinning?)

My guess is that you are using a the speakers outputs from the deck to the highlevel inputs of the amp. If not then disregaurd the rest.

Some people tend to like the effect using the high level inputs on their amps make the total signal a lot louder. In my opinion it causes more distortion and over drives the amps.
I had a car recently that had a factory amp, and it was doin the same sounds of the CD spinning. What may be happening is low level noise i.e. from the CD spining can be picked up by the signal. But these noises from the radio are very minute and dont increase when the volume is increased. In the case I had, all I did was bypass the factory amp and run the deck straight to the speakers. In your case you'll have to run RCA lines from the radio to the amps.

looks like a bad batch of pioneer HU. I'd suggest get a new headunit.

Side note you are not using the high level signal from the HU, you are using the pre-outs. I dont think that a ground loop isolater would do the trick, because its imbedded in signal lines and shouldnt be a case for the faulty install. Its worth a try. Also try regrounding your amp and HU and attach a ground wire between the amp and the HU. usually some rca wires have a separate wire attached just for that.