Old System New Popping

I have been installing car audio for about 13 years now and I can't figure this one out.  I have had a system in my car for over a year now and yesterday when I got in the car and started up the engine I got these unbareable pops (boom, boom, boom,...) the sounded like my head unit was on full blast when in fact I had turned it down to ZERO.  I turned the system off.  Shut down my car, checked everything in the trunk and it looked OK.  I turned the system back on without starting the car and got the same thing.  I waited about an hour turned it on and it would play but there was a whine with the engine off and the levels were severly low.  I repaced the head unit today and I still have the same problems.  I don't have any equipment with me to test my amplifier but I would like to get this taken care of while I am still away from home.  I can play the new head unit with normal levels but the whine is rediculous and the popping when I change between sources is unearthing.  I also hear my CD player spin up and search.  This is very annoying as well.  I didn't have this problem for the last year, it all just started yesterday.  Can you offer any suggestions.  I was contemplating changing out my high side amp.  

Head Unit  Pioneer DEH-P80MP

This is my new setup after changing out my head unit.  The system played for a few days normally after I replaced the head unit and all I heard was alternator whine and the pop when I transitioned from 1 to 0 on the volume level.

I pulled the RCA cables from both amps and the buzzing and everything went away.  So the problem is between my head unit and my amps I agree.  I found out that if I pull either one of the RCA sides out of my sub amp the bbbbbbb problem goes away.  There appears to be some sort of loop created when I plug in both right and left RCA's to my sub amp. 

I will check my RCA cables front to back and fill you in when and if I find anything.  Thanks for the input.

I pulled the power from the sub amp and my highs amp popped with the same noise.  Then when I put the power back in and pulled the power from the highs amp the sub amp really rumbles, until, I pull out one of the RCA plugs.  I replaced my RCA cables and still the same thing, both amps making that bbbbbbb sound. 

What I am wondering is, could something in my alternator have gone bad to blow both of my amps?  Has anyone ever heard of this happening?  I don't want to replace both of my amps until I find out what caused my other ones to blow!!!

Any suggestions.

You replaced the RCA cables completely?  Sounds like a couple possible causes might be

1) bad or loose ground somewhere, maybe at the amps, inside the engine compartment, at the battery or at the HU 

2) Head unit went bad.

Today,  I used a jumper to connect the accessory wire to my remote to turn my amps on and I plugged in a portable CD player.  Everything worked fine.  So, I have to go get another head unit to replace this one.  I have never installed a head unit that was bad out of the box, what a pain in the neck.

Thanks for your help,