Help! Pioneer Deck and a popping sound.

I own a Pioneer DEH-6400.  Everytime I lower the volume all the way down to 0 it generates a "pop" on the Left Rear channel both on the hi level and lo level outputs.  This also happens when i switch sources and use the Easy EQ button.  It is only one pop per button press not a constant popping.  It is very annoying and you can imagine what a simple pop sounds like when its run through 1200 watts of power.  I tested everything.  The patch cables, power connections etc.  and nothing.  My co-worker suggested it might be the internal power supply.  Are there any other suggestions?  Thanks in advance.

Did you use the ground wire in the factory harness?  If so, it could be an insufficient ground.  Try running a new ground wire direct to the car's chassis.

I had a custumer with the same model radio , I suspect that is the rca output of the radio, Unplug them and connect them to the front outputs if pop goes away is an internal problem. Good luck let us knowLuis

Sound Waves

Is up to the installer to test all wires with a DMM whenever possible.

No, i used all new power wires. New ground, New constant and new acc.  The popping persists through the speaker level outputs and throught the RCA's.  I do believe it is internal. Off to service, i gues. -Thanks.