That's what I thought as well. But all the whine is gone after I switched from my old Clarion unit to an Alpine unit...
The only oither changed variable was the RCA interconnects. I have 2 of them, one for front components and one for sub. One (the purple KoolKonnectz) was run down the driver's side of the center tunnel, and the other (the blue KlearKonnectz) was run down the passenger's side of the tunnel.
I was originally using the supposedly higher-quality KlearKonnectz for the components (they are twisted pair, whereas the KoolKonnectz are only "shielded"). Now I've switched it up and I'm using the KoolKonnectz for the front components.
So the only possible explanations for what happened is:
-better head unit
-KlearKonnectz is worse than KoolKonnectz cables (contrary to marketing)
-huge difference of noise in the 6 inches of differnence between each side of the center tunnel
Just FYI, the car in question is a BMW E36, a car notoriously known for it's alternator whine.