Just picked up a gorgeous Charcoal K250-2 head, sounds fantastic. This is the first 250 series head I've owned, have always had the earlier 200 series. The locking reverb was a new one to me, the "illustration" around it makes it look like you should rotate the knob to lock/unlock. I had to actually pull the knob out a ways to unlock it....and then pushing it back in locks it. I take it that's the way it's supposed to work? I know, I know....a trivial question.
I was surprised to see only one speaker out jack on these heads, my old 100's & 200's had two jacks. I would have assumed that these were originally sold in two-cabinet configurations.
Love the head, gobs of power!