ill do my best to type this all out and make sense of my mess.

i just bought my player and am installing it into a center console. i already have a eclipse deck that i wanted to run it through, using its aux. the eclipse is too old and doesnt have that option so i tryed a whole mess of "y" connectors . after i had all of that worked out and started it up i got a terable buzzing noise. it was shooting a 50 hertz note into the subs and the mids and highs both had different tones coming out of them. after i couldnt take the buzzing anymore i took the connections off the back of the empeg. i drove by my local car audio store and asked a few questions . they seemd to think i was getting feedback through the rca's. so i started looking at pre amp eq's with aux switches. after getting one of those and installing everything again i still had the same buzzing. so in this situation i should have absolutaly no way to have feedback through the rca's. then i tryed unplugging the rca's from the eclipse and just running the empeg.
WORKS BEUATIFULY
so basically as long as i have only one deck hooked up, doesnt matter wich, everythings honky doory. when iether or is hooked back up it starts with the buzzing again...
im at a loss. every1 i know is dumbfounded.
i even went as far as to give them there own grounds, power and memory wires. they almost are compleatly separated from each other.
anyway, any help or advise you could give would be gladly appreciated.
thanks