I have run my xm radio throught the aux using rca's in the back of the deck. With the deck off, I can turn the aux on(on the deck) and the whine starts. Then, I can turn the power to the xm on and the whine still remains. With everything off, I can turn the power to the deck on to listen to the regular am/fm and the whine starts again. Anytime I turn either one on, the whine starts. I pulled the deck out of the dash(when I was experimenting with the different ground places) and the whine was the same as if the deck was mounted in the dash. All grounds from the factory ground, the deck ground, and the xm ground are wired together at the same place. As stated above, seperating these grounds did not make a difference. I even did as one person suggested and move the xm antenna wire(I actually unplugged it from the xm radio) and there was no difference. According to him, the power wires run along the passenger side of the car and sometimes with an aftermarket deck, there can be some feedback and you have to reroute the speaker/antenna wires to the middle of the car or the driver's side. But, in unplugging the antenna, there was no change.