I've heard them on several occasions, very impressed. If I was going SS, which I'm not, then Constellation, Dartzeel or D'Agostino, would be where I would be looking.
The best value in the insanely price world we live in, would, for me, be the Dartzeel integrated, an amp I prefer to the companies Pre and Mono blocks. I've seen those under £9000 second hand, still very costly I know.
As an aside, I've seen D'Agostino Pre and Power amps, three months old, half price second hand. I know there may be some financial or personal crisis underlying this. If not, what sort of sane person spends north of £80,000 on amplifiers and tries to sell them second hand three months later, for half the price.
If anyone knows who it is, I am raising money to build a canal across the Amazon, very good investment opportunity.