Success at last!
No more ground loops..no more whine!!!!
Here is what I did:
Grounded the sled to a grounding point other than what the HU was grounded to! I had previously tried to ground the sled to the same point as the HU but the whine was the same.
This morning, after looking over all the wiring, on a whim, I jammed a wire between the sled and the player and pressed it against the cigarette lighter socket..and BEHOLD..whine disappeared! I felt like I discovered the Grail!!
Then...I tried to reinstall my Sony CD receiver so that I can use the tuner as well as play mp3 cd's. into the AUX input..but still had the damn noise..so again, on a whim, I installed an RCA noise reducer between the Sony and the Rio..and BEHOLD AGAIN! absolute silence!
Beleive it or not this took a FULL YEAR to trouble shoot and I couldnt be happier.
I have been on these boards for all that time looking for suggestions..which included grounding the sled...but who know that it needed a different gound point!
Well, anyways...that's my story and I am sticking to it!
Thanks for all the help guys!
Ed
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...One man gathers what another man spills