Well Phreak the amp isn't in contact with anything other than the wood amp rack I made, and all it's connections. That was the first thing I made sure of.

I checked the RCAs ins on the amp and I got

1.1v

I then checked the RCA outs on the HU and got

5.2v
10.1-10.9 ohms on all the outs.

I'm going to check with Pioneer and Sundown on what's acceptable.

 

I went and got a set of cheap RCAs and got the same thing. I made sure the RCAs were not touching any part of the car. I tried turning the amp gain all the up, and found that the problem goes away. Once I start turning it down, the noise comes in. I tried turning the gain both ways and got the same thing. I played around with the filter settings, and got no noise at startup on low pass. I switched to full and adjusted the gain, and the noise came back. Now I also ran the front HU pre out to my sub amp, and that played fine.

Now I am completely stuck. I've got one more idea on grounding, but that's all I could come up with.

 

I believe I found the problem. As soon as I get everything changed out I'll update.

Thanks for all the help everyone.

 

updates?

 

I ordered a bunch of things per the recommendation of another member

I got
50' of red 0 awg cable
50' of Black 0 awg cable
0 awg to 4 awg reducers
XS power battery with new terminals and GM terminal side mount add-ons
Techflex insultherm sleeving
Plenty of ring terminals

I'm nipping this in the bud with a cutting torch.

 

Ok I got everything finally.

I hook up everything, then all my amp fuses went. So maybe next week I'll be able to tell anyone if anything works.