Whenever my HU is out for service (don't ask), they give me a lower end HU as a loaner.
The low end ones always seem to let a little whine through in my van, but my own HU NEVER lets whine through.
So, I'd think that GL isolators would be a good bet, assuming your RCA's are run cleanly through your car.
Either that, or when you've got all that whine, get some cheese, have a party.
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95 Astro Cargo Van
KW KDC-X979
DVD, XBox, Sirius
RF Punch 55.2 - Orion Cobalt 5 1/4's
ALP V12 - KW KFCX698 6x9's
CLAR APX400.4 - KFC-X698
(2)Orion 1200D - (1)Orion H2 12.2
Roger Waters June 23rd Pengrowth Saddledome WooHOO!