Here's my Tower of Doom in all of it's 2.67 ohm glory. While Mesa's "recommended load" is 4 ohms, I could probably get away with running it like this for a short time as long as there weren't stage lights bumping up the heat level--the fan works pretty well, too. After a 3 hour+ gig, the Mesa is never even warm to the touch. Still, will probably never happen--I've been gigging fine using only one of the 1x12s, so I've no real need to drag all of this stuff to a show. I just thought it looked cool. *cat shown for size illustration purposes only. Not required for actual operation of rig.