exactly my issue!

The interesting thing is that i had originally grounded the sled to the grounding point in the trunk where the HU was grounded. Nothing changes (i.e. whine!)

On a lark, I jambed a wire between the sled and the HU and touched the metal ring of my cig lighter..and the whine disappeared!

this lasted for a few months until one of the pins on the mother board from the IDE cable plug dried up....get the No Hard Disc Found display..doldered the joint back..but the whine did not go away!

So now, when I run the RC's to the Sony and bypass the Rio..crystal clear..when i run the Sony into the Rio and run the RCA's out o the Rio and into the Amp..i get whine....

so maybe i need to re-run the ground from the Rio to the front of the car from the rear where the amps are grounded?

Should I then run 3-grounds..the Rio, the Sony and the sled all to one point in the front (original wiring harness ground or separate?)

Thanks!

Also, how does one go about grounding RCA cables,a s it was suggested where they go into the amp?

Ed