Heat sink on the head unit in my car is getting extremely hot, and I can't figure out why. A little back story: (96 Subaru Legacy Sedan) I've had the system for about 2 years and this is a new problem that began to occur after I simply took out the subs for trunk space and put them back in a few weeks later. The first time it happened, I was playing my music for a bit until the subs suddenly stopped hitting. Music was still playing through my door speakers, but nothing coming from the subwoofers. I wasn't sure what the issue was so I replaced and re-wired the harness that comes with the head unit, replaced the "Radio" fuse which seemed to have melted slightly, and still nothing. My 4 door speakers are all 4ohms, as well as the subwoofers. The head unit is a Kenwood dpx792bh, which the manual says is meant for between 4-8 ohms. The head unit will heat up to the point where it cannot be touched, whether or not the external amp (1000w) is hooked up or not. The external amp turns on and has never gone into protection mode, or overheated. I'm hesitant to take my car into an audio shop that will charge 3x what it will cost for me to fix it. Any ideas? All help is greatly appreciated!