hello im new to the bass world. i was the singer in a band but we lost our bass player so i said that i would fill in and i love it. so it got more intense. well my question is. . . i have a swr working pro 400 watt head and a swr 4x10 working pro cab. what i need to know is if and when i get a new cab to run 8x10 do i just need to get a biger head or can i get something to up the watts on the head so that it can fill both cabinets???