Well , Spritzer and Schubert are right. The Pessante 2U is a tight fit
Only 10 mmm clearance from the heatsinks to the top cover, which means 6-7 mm risers at most. I am thinking on applying some sort of insulating material to the bottom cover as well, without obstructing the vents. For the top, I purchased the one with the vented covers, like Schubert's.
All boards are up and running, with balance at +- 0.3V and offset at +- 0.5V, temperatures in heat-sinks between 49-54 centigrades, higher in the amps than the PSU. Very stable and easier than my first KGSSHV, which took me forever to adjust. Ranges in the first build where +- 1V for balance and +- 3V for offset.
This one also has the IXYS parts. Reserving the 1968's for the Megatron.
Now comes the hard part.