First off why the hell are you wiring up 6 subs? Maybe if you have 1-2 good ones that would solve your problem.
Home audio receivers are only stable at 8ohms, some will do 6 at best, so you're overdriving the amp. Figure out how to wire them or some of them to a load your receiver can handle.
My son hooked up a 4ohm car sub to a decent Pioneer receiver I had and cooked it in a matter of seconds.