I have checked the grounds and everything looks fine. I have had the sub and amp in the car for 6 months now and never noticed the whine (probably because only the low tones were being reproduced. Since last night, I have removed the amp for the interior speakers and hooked them back up to the outputs of the head unit and the whine is gone when playing cds and listening to the radio but when I play a dvd, the lines are still on the screen and the alternator whine is still there in the dvd audio. This is hooked up to the same ground and power as the sub's amp. I have removed the 2 rca cables from my door sills that carried the 4 audio channels to theamp since the amp is now gone. So now as far as cabling, I have:
RCA to amp form head unit
RCA from DVD to head unit
RCA Video from DVD to glove compartment
Remote sensor cable from DVD center console
Left and right rear speaker wires from head unit.

I am guessing this is a problem with interference rather than alternator whine because the LCD screen is wired in to the same circuit as the head unit and grounded the same as well (used wires from factory harness that were connected to radio), and I still have video interference. The only thing I have not tried is pulling out the videoa nd rca form the dvd and just running them outside the car to the trunk to see if thats where the interference is or if it is somewhere else.
Thanks.

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89 300E Pearl Grey Metallic
7 Spoke 16" staggered wheels (SLK)
215/55/16 Hankook Ventus HRII H405 tires
Euro Headlights
Smoked Corners
Smoked red/clear tail lights

1987 300e Black Metallic (mom's car)
8 hole 15" wheels (C Class)
Clear Corners
Red/Smoked tail lights