*Very* interesting amplifier, thanks for posting.
They turned an industial motor controller into an audio amp. Cool .
Searched for the datasheet, no mention of this use, so I guess only Peavey(who invented it) understands it.
*If* I had it on my bench, and thanks to it having separate boards for everything, I would pull the digital power amp out, keep everything else and mount one of my own 300W boards, which would be happy with those +/-60V.
Analog classic board, of course.
But that's me, of course.