I installed a new deck today, pioneer 7800 mp.
I have two amps, one 600 wrms for the speakers and another 800 wrms for the subs. I play the music at 3/4 volume for a couple of minutes and then all of the sudden, the subwoofer emits a very HIGH pitch continuous tone and all the speakers don't work. All I hear is BEEEEEEEEEEEEEEEEEEPPP coming from the subwoofers...the Beep is so loud that my hear went ringing for a couple of minutes...

What happened? When I open the radio it still does the same.

I have 2 AWG wire splitting into two 4 AWG for both ground and +.

 

Sounds like you might have a problem with the rca ouptuts in the deck, I repaired a buddy of mines Pioneer that did the exact same thing, his was one of the rca`s in the deck used a pair of wires to transfer the rca`s from the Printed ciruit board to the rca`s in the back panel of the deck, they had a break in them and once you turned it up the bas vibrated them and caused a short and the amplifier basically amplified a real high pitch beep\squeal

Not sure if yours is the same problem just thought I would give you an option

Garett