Electrical feedback sound coming from subwoofer?

[Password]

I think this may be related to my aftermarket radio, I'll explain that below after my description.
After starting the engine theses past two weeks, there will be a whine coming from the subwoofer that will last for about 10-20 seconds then die off. I will also hear a subtle pop feedback from applying pressure to the brake pedal. Is this sound like an alternator issue or maybe because of the story below?



I swapped out my 6 disc CD headunit about two years ago and ever since then, I could never get rid of the start up and shut off pop from the subwoofer. I tried two 12v to 5v converters and neither one stopped it. Tried running the grounds all the way to the chassis ground in the engine bay also, but no luck. I think it has to do with the all-in-one Crux steering wheel control/radio wire harness still letting 12v go out somewhere. I bought the metra harness, a different steering wheel controller and another 5v converter and will swap it all out this weekend to see what happens.

 

[Cooper]

What amp, headunit,, rcas (twisted or shield), and gauge wire are you running? Didn't you upgrade the power and ground on the alternator and battery ground. Do you have a extra battery in the back and did you run a ground from the front battery to the rear or used a chassis ground?
Make sure sure the RCA are not ran parallel with power wires

Also just for giggles disconnect your rcas and start up the truck just to see if you hear any feedback or distortion at all. If so you will know its either the amp or the ground or the amp.

Lastly make sure your gains arent turn all the way up lol

 

[Password]

Got it sorted out. No more thump or electrical noise. Either the Crux harness had issues or it's garbage. It could have something to do with the Crux harness having the C240b 16-pin connector and the Metra harness does not.

Now my gave myself a new, bigger issue that probably needs it's own thread.