Originally Posted by gijoe View Post
In my experience, routing RCAs close to power wires rarely causes noise. I'd take a closer look at your grounds. You have a DSP, an amp, and a head unit, are they all grounded to the same spot, or different spots?
I started from a presumption that it was ground related as well, but have not had success pursuing that option. Currently amp and DSP are grounded together, with head unit grounded to factory wire. I did try bringing ground from the amp/dsp point to the head unit with no success, didn't bother routing wire through dash after that as it is a pain in the ass due to the car's size and low stance. Ohmmeter shows near 0 resistance between the two ground points, but that obviously isn't completely reliable.

Originally Posted by OldNewbie View Post
I agree with gijoe. These issues are normally ground related. Have you tried rerouting the RCAs or the power on a temp basis to confirm the noise is due to due proximity?
I did run a long RCA out and around, and whine levels varied depending on how close you got to the battery area. Never could completely eliminate them though that method, which I attributed to the fact that my extra long RCAs were completely unshielded cheapo home variety that I had sitting around and not quite long enough to go completely out and around.

Originally Posted by Truthunter View Post
Have you unplugged the RCAs from the DSP inputs to see if the noise persists?
Noise is eliminated if you unplug source RCAs from the DSP inputs.

I should also note that originally the system used a Nexus 7 tablet as a source with a USB to Optical DAC that fed the DSP via Toslink cable. Never had any noise issues with that setup at all. Only surfaced when I switched to the Sony. Had backup cam and charging issues with the Nexus, so I ditched it.