I have the D2 that I just installed in a Mercedes E430. It sounds fine when the ignition is turned to the first setting which I think is acc but then if I turn the ignition to the second position, before starting the ignition, I get this high pitched whine. It does not seem like alternator noise because the intensity doesn't increase when I start the engine or increase the RPMs. The noise doesn't increase if I change the volume on the avic but does if I change the gain on the amp. Also, I've already checked all the grounds and tried grounding the RCA shields to the chassis and or the avic body with no help. I've tried a noise isolator which gets rid of the noise but distorts my music so it sounds like it is under water. I'm not sure where to go from here. The yellow and black cable from the avic harness go to the little black box and fuse before connecting to the Batt and ground but there is also a second black on pin 3 which i connected directly to ground. Is this right?

Also, I've already checked all the grounds and tried grounding the RCA shields to the chassis and or the avic body with no help. I've tried a noise isolator which gets rid of the noise but distorts my music so it sounds like it is under water. I'm not sure where to go from here. The yellow and black cable from the avic harness go to the little black box and fuse before connecting to the Batt and ground but there is also a second black on pin 3 which i connected directly to ground. Is this right?

Congratulations, you've created a ground loop.

Basically, grounding is your problem. NEVER connect the Audio ground to chassis ground - they are different. The only pins that should be connecting to the chassis are black *power* grounds, like that which runs along side the yellow cable you've already mentioned.

I'm not sure what "second black on pin 3" is referencing, but I'm fairly sure it should NOT be connected to chassis ground. Try taping it up and seeing what happens.

OK DUDE

i believe u said u have a 4 channel amp. what brand/ power rating? how did you hook it up? did you run speaker wire to all the speakers or did you just run them all up to the deck. if you turn your gain all the way down does the noise still exist?