The Quad 57s run 6kV on the two bass panels and specified for 1.5kV on the treble panel. I remember Roger musing that he wanted, I thought at the time somewhat ambitiously, to run 1.8kV on his Quads. I always thought that would be pushing them a bit too far as the classic design is already quite prone to arcing over at higher volume. It was to do with lowering the distortion IIRC.
I’m not that familiar with the Acoustats but have heard them. How did he improve dispersion? Are there multiple tweeter panels on an Acoustat so you can use different phase to each, like on the Quad 63?
It would be brilliant to get Majestics going with direct drive, if you can make it, do! I’m sure Roger would have loved that. (Be very careful with instantly lethal voltage on the tube voltage power supply!!!) You’ll need to have a good working knowledge of their characteristics first, and liasing with Soundlabs would be the way to go I suspect.