Ehhh might have been 290. I was just doing this off the top of my head but the full data should have been posted here by me at some point. 290V sounds plausible as it is half of the B+ minus the natural loss.
Mine are built with the boards attached directly to the sinks and I adjust them from the top. The boards you are using are different from mine though and I'm not sure what version was used on the groupbuy...
That has its own issues due to the proximity to the output socket and its wiring. Much harder to shield that with all the extra capacitance the shield would generate. It should be clear now just how much engineering went into the KGSSHV mini...
Yeah, the Stax thread over there is just an endless stream of bullshit. Most of the advise given is inaccurate or just flat out false. Stupidity is the new norm....
Ahhh saw the batteries. I bet that is the noise you are hearing, throw some Xicon's in there and it should work just fine. Low noise maybe but not Carbon levels of utter dead silence. Just can't be done with that T2 circuit.
The SRD-7 never shipped with that crappy connector and velour pads on Stax are pretty high on the stupid scale. Go read a bit about how an infinite baffle works on dipoles...