I've been playing bass for about a year and a half and when it comes to amps I'm clueless. Anyways I bought a 100 watt fender rumble series amp from guitar center a few weeks back. Good solid amp. But eventually I figure I'm going to need more power and I was wondering if there was any way to power it up even more. Could I add a cab to it or something. I looked on the back and there's no 1/4 jack. But on the front of the amp it says effects loop: preamp out, preamp in, XLR Line out.Can anyone help me out? Thanks in advance and I hope this wasn't a really dumb question.