here is the power supply with a screen dropping mod on the std by sw,
it is called Yield (lower power) on the front panel, the amp sounds pretty good with the 2 x 10 spks, , 40:1 OPT so about 6 or 7 k to 4 ohms,
Very interesting. I have an old Standel that has 400 plus volts on the 6bq5’s with a 110 ohm on the pair of output tubes for cathod bias but uses 150 volts on the screens to keep them from frying.