ground loop noise

hey, i am having horrible alternator noise and i have done all the regular things to troubleshoot it, reground amp, HU, and line driver. I also unplugged the rca's from HU and hooked up an ipod. this killed the noise, so i am fairly sure it is the Head Unit. Like I said, I have regrounded everything, and I have also metered them, all of my grounds read about 0.4 to 0.6 ohms. My only thought now is that the vehicle battery does not have a big enough, or sufficient ground, but i am not sure that makes sense. I have a 2002 Mitsubishi Montero Sport. I am running an Eclipse CD-8053 HU, with a Balanced line adapter line driver that bumps the line voltage to 16v. that goes to a Rockford Fosgate Power Series T4004 4 channel amp that Pushes front stage MB quart Premium series components, and rear stage MB quart Discus series Coaxials. All of this is being powered by a red top optima battery, and I also have a Kinetic battery back by the amp. My amp and Kinetic battery are grounded in the same spot. I have pretty much ruled out faulty equipment because all of this was just taken out of my previous vehicle. any help or ideas would be greatly appreciated. THANKS!!!

I just relized I never hooked up the antenna, therefore the headunit does not have its own chassis ground, could this be the issue?