i grounded the deck to the chassis right behind the deck. the ground cable i used is less than 8inches long. It didn't make a difference. the alternator whine that i hear is quite quiet, but it's when you have the volume abnormally low, you will hear it. I still am determined to get rid of it altogether.

i didn't know you can get sheilded speaker wire cables.

but even when i disconnect the speaker cables going INTO the amp, so it's just the amp and the speakers it is driving operating, you will still hear the whine. Shouldn't that elimate what is upstream of the amplifier...at least for now.?