I had a GBE750 once. Beautiful.
Unfortunately, it hummed like an angry bee whenever I went within five feet of it.
Both Genz and the UK distributor spent a lot of time trying to resolve it, but without success. I had to send it back.
Gutted, as I REALLY wanted to use it in the long term.
Anyway, you can't beat an amp with a transformer in it.
Class D? Meh.