Hey good afternoon folks...

My sound system is messed up...

Once I turn the engine on, and if the head-unit is on, there is an extremely loud hissing/buzzing sound. So I turn off the head-unit and the hissing sound becomes much lower but remains. It'll remain like this for at least 3-5 minutes as I drive around. Once it goes away, I can turn on the head-unit and 80% of the time the hissing sound won't come on with it. But if it does while the head-unit is on, it will be much more tame and I just blast my music like usual and I know it will go away within 1-2 minutes.

If I listen to my music at the loudest levels for at least 20-30 minutes, then the hissing sound will start creeping in along with the music and it won't go away unless I turn off the engine and all electrical power (turn key all the way).

If I turn off the engine and power for about 1 minute and turn it back on, the hissing sound will return and I will have to wait 3-5 minutes like usual for the hissing to go away before I can use the head-unit.

The colder the weather is, the longer it will take for the hissing sound to go away.

Sometimes the right rear speaker or front right or front left speaker will do a spooky static sound regardless of whether the head unit is on or not.

So is the black HK amp in the rear messed up? Is it possible that it's just a bad ground? It looks like I have to remove the rear seats and the entire passenger-side rear cover to access the amp, which is totally lame, right?

If the amp is messed up, I can't replace it with any other amp, right?

Thanks for the help!