Audio Systems: aftermarket car stereo noise, kenwood kdc, acoustic amp

Question
Greetings,
I have a fair amount of electronics experience (5 yrs in copier field) but very little in car audio. I recently installed an audio system in my 1997 Taurus and have been experiencing an undesirable noise. I am running a Kenwood KDC MS 5028(fairly high end w/mp3 wma capabilities etc). I am also running two amps. Phoenix Gold 90w/channel @ 2 ohms with four 4 ohm speakers wired in parallel for imaging, and a US Acoustic 600w/4ohms into the sub. The noise is hard to describe and is present with the car running or off. At times it sounds like radio static in the background. Other times it can sound like a crackling sort of hum that will get VERY loud regardless of the volume setting. I am using separate grounds at two different points on the frame for my amps. So far I have replaced RCAs with new ones, changed head units, and swapped out amps to no avail. All 12 volt wiring is running down one side of the car and RCAs on the other. When I initially installed the entire system it sounded good for about an hour. Then I replaced my old RCAs with new twisted pair RCAs. No help. Then swapped amps this changed the sound and pitch of the noise, but did not seem to fix anything. The last thing I changed was the head unit. Then the system worked good for about an hours worth of play then began to develop similar noise and symptoms that will not go away.
Any advice you have would be greatly appreciated. I have been working on this thing every day for more than a week.

Thank You,
Brad


Answer
strange. sorry to hear your having such trouble with it.  sounds like you did everything right though. first thing I would try is disconnect all the rca's to everything and turn the system on.  If you still get noise then theres something causing it in the amps.  if the noise goes away the problem is either in the cd player or a ground loop between pieces of equipment.  I had a us acoustic amp, they are pretty crumby, I seem to remember a simliar problem.  If there is no noise when the rcas are out I would turn the system off, connect 1 phoneix amp to the cd player ONLY and turn it back on. see if the noise is back.  if its gone keep adding amps until the problem comes back.  
These things will help tell us where the problem is.
Let me know what happens.
Good luck!