The PCBs were a bargain, but their size and dimensions limit one's construction options. I was considering cutting off the two amp sections, and then using two small 250-0-250 @ 40-50 mA trannies that I salvaged from fome old Heapkit test gear, and then make little micro- monoblocks, or at least a "dual mono" design. The micro monoblocks could each probably fit on and into a 6 X 4 X 2 box, with a little creativity.
Without the PSU section in the middle, the stand-alone amp sections are less than 3 inches square, and each already has four mounting holes.
I know, it's serious overkill for such a simple design, but then it sounds like it could be a fun project...
From the 6T9's pentode ratings, it looks like they can be pushed a bit harder than the "gizmos" design, with no ill effects. I'd go with 275 V B+ and 35 mA "zero signal" idle current.
/ed B in NH