I had the same problem. I think it was my AMP ground which gave me the "whine" I have the Kenwood Excelon z828.........either ground your headunit to the same ground as your amps, or run the cables on another side of the car..

Hmmmmmmmm.........

1998.5 T-RED SVT
18" Team Loco 142's W/ Dunlop Rubber
181.2hp@6900rpm/155tq@5000rpm
LOTS OF MODS OF EVERY KIND....
...Am I a guru yet??? No... not yet.