So I've gone through 2 subs now...

hey bro it sounds like your amp is simply overloading the subs please dont tell me your running like zero gage to this poor amp i think you should try 8 gage solid copper wire like telephone wire it has the best conditivity that i have found and try re tuning your head unit to a different frequensy and matchin the amos to that frequensy and dont pump the amp all the way up either ..................................................................................................
If you keep running into problem hit me up and i can run ur senario passed a few freinds whom have taught me alot ok
Patrick
CJC

Gain=Volume. The gain on your amp is to match it to your volume on your headunit. But another great debatable point.

Not bashing your suggestions just stating my opinion.