Audio Systems: Subwoofer Feedback, rca cables, line output converter

Question
Scott, I was hoping you could help me.  I have a 2000 Cadillac Deville with a factory radio.  I have a line output converter installed and rca cables going to my amp which i have powering 2 12" subs.  I have the remote wire to the amp running to the ignition fuse in the fusebox, and is ran to a toggle switch.  My trouble is that when my vehicle is RUNNING and the radio is OFF, if I turn the switch on I get feedback from the subwoofers as if my radio was turned up and they were hitting a constant deep bass note, and it doesn't stop until I turn the switch off.  If my radio is on the system works just fine.  Any help would be much appreciated.

Thank You,
Jeff

Answer
"I have a line output converter hooked up to the factory subwoofer speaker wire" may be the problem. If the LOC is connected to the factory amp, you run into problems like this.

You need a factory bypass harness to the LOC for it to work correctly. You can get one from here http://www.metraonline.com