high pitch tone, then pop

I've noticed a couple of times when I start my truck, theres a high pitched tone, then pop. Then everything works fine. I sanded the paint off the body where my ground is again and bolted it back. It hasn't acted up again...yet. But I noticed before I resecured the ground, the alpine amp I have was reading 14.0 volts, now it's reading 14.6 when I start the truck, then settles down to 14.1/14.2 I also took a Ohm reading from the battery terminal to my ground termimal and got 0.01 If this pop comes back should I look at the RCAs? The pioneer HU has an adapter plug for channels 3/4, maybe it's the plug in the HU? as I notice the sound coming from the rear speakers the loudest.

The pop is still there, it's loud too. Had something like this happen a few months ago and it was the fuse holder set screws on the cable that came loose. I noticed the pop is all the speakers, not just the rear. I've ran new jl brand 4 ga,(for the sub amp) and new streetwires 8 ga. for the 4 channel amp. Streetwires LN5 RCAs.

Heres how I installed everything. Ran both power wires down drivers side through the emergency brake grommet (to avoid cutting cables). All RCAs ran down the other side, along with the speaker wires. Front speaker wires are ran through the door molexes (x-overs behind kick panels) Rear speaker wire spliced behind HU. Cut the speaker leads out of HU harness, now that I'm using RCAs for 4 channel amp. Grounds ran from the amps are together to a bolt in the floor. Also grounded HU to firewall (Ohm out at 0) Added 1 4ga ground so far from batery to frame, along with the factory wire. I only notice the pop now when the trucks moving. Does this sound like a ground loop? should I run grounds from amps to battery? The bolt I'm grounding to is actually the rear seat bolt, but checks out to be 0.01 Ohms. Both ground terminals are bolted there.

Ok, I've narrowed it down to the right front speaker. I'll switch the RCAs left/right at the amp. If the left speaker pops then it's the cable or the LF output of the HU. It's an intermittent problem, and the pop gets louder if the volume is louder. The cables are not kinked anywhere, and are brand new. Any other thoughts on troubleshooting this intermittent problem? I'll check the speaker wire in the door tomorrow to see if it got kinked somehow.

OK, I'm an idiot. Under my amp rack I noticed the rca from my sub amp was looped around the power and ground wires. I'm pretty sure that was the problem, because I unplugged the rcas from the 4 channel, and still heard the pop through the subs. Ran it for 30 minutes and I haven't heard any pops yet. Sometimes its better to keep your mouth shut and be thought a fool, then to.......OK....ya know the rest.