I've thrown this suggestion before, but I wanted to offer up my solution... I picked up a powered 12" monitor from MusiciansFriend's Stupid Deal of the Day for $99. I run either my gig board which ends in an Aguilar ToneHammer (below) or my Zoom B3n and am happy as can be. I like this solution enough that I'm really debating getting rid of my other amps (I've got a few solutions) and picking up a couple more monitors (when more power's needed). I play a 5 string and this setup handles a low B like a champ and it keeps up with a reasonable drummer and guitar player quite fine. This monitor is fairly light too, so it's a win all around.