I picked up an almost new GK 210SBX off of ebay. I tried it with my GK 1001RB II, but after playing with a couple of guys in a garage for about an hour and a half, the speakers started to rattle. I knew goin' in that I was probably over driving the cabinet even though I never got over 5 but I figured if it didn't hold up, I'ld put some better speakers in it. Today I put 2 10" eminence kappa pros in. I plugged in my 5 string Warwick and the speakers rattled off the low B and open E with the GK 1001RB II. I hooked up my 400RB and got about the same thing. I'm wondering if porting the cabinet would let the speaker perform better.