I have the AVN2454 installed in my 2004 6MT G coupe. It's being powered by a Diamond Audio 600.4 amp and I have a 10 inch Diamond sub powered by a Diamond 600.2 amp. I also have an XM commander that's plugged into the AUX input of the AVN2454. My problem is that I have a loud whining sound when I put the car into gear and accelerate. It doesn't whine when it's in neutral. I brought it back to my installer and he said he doesn't know why it's doing this. The power cables and the speaker cables are all ran on opposite sides of the car and he thinks that it's the XM Commander interfering with the AVN. He insists it's not a grounding issue and that he's had the same problem using the same combo in a Ford truck. Have any of you had this problem?