I have a GK 400RB-III (240 watts into 8-ohms / 150 watts into 4-ohms) and an Eden D-210XLT 4-ohm cabinet. (rated at 350watts). I like the sound. It handles the 5-string. I can carry it around easily. It's loud enough to compete with a drummer. Everything's just great. But in a big room, it can get lost. The amp has 3 knobs that mean "louder" in various ways, and they are typically set around half to 3/4. Turning them past there, in any combination of pre/post/boost, causes distortion. Can I add a speaker cabinet to this setup, modularly, so I just bring the second cab if I'm going to be in a big room? If I had a duplicate cabinet, the sound should be about the same but more air would be moved. That would be a 2ohm load though. If I got an 8-ohm version of the cabinet to add in, the total load would be sqrt(12)? ~=3.5ohms, which is close enough to 4, where things presumbaly won't blow up or anything. I could get an 8-ohm cab, and trade the 4-ohm cab for an 8-ohm cab, but that's a lot of work. Any other ideas? Would getting a duplicate cab in fact solve the big room / distortion at loud volumes problems?