My bassist has a Peavey Firebass 700 head and a Hartke 4x10 cab. We have two guitars with half stacks in our band and a heavy rock drummer, so the bass wasn't quite cutting through. Recently we added a 1x15 cab with an Eminence Kappa speaker and it did not last very long. I had the 4x10 and the 1x15 hooked straight to the back of the amp and the 15 blew within 10 minutes. I was wondering, did this happen because I plugged both cabs into the back of the amp? Should I have linked the two cabs together and then plugged just one into the amp?