Re: Stereo RCA's blown?
There's probably a ground loop between the HU and amp. Connecting RCA's connects the amp and HU grounds together. Engine whine, pop, etc are usual symptoms. Using speaker level inputs eliminates the inter-ground connection. Proper solution would no doubt have revolved around regrounding HU and/or amp.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's