Rolf,
thanks, at least one who has heard it before. Seems it's totally unknown in the US
My local tech guru said immediately when he saw it: I've bought a nice eyecandy (as usual), not perfect for highend 'as is' nowadays, an excellent basis for modifications though. We hooked it up and he was right: very clean and powerful amp but, uhm, still improvable.
He knows his H/K stuff very well, and uses the units preferably for his tunings. He will get it tomorrow, first thing I guess he will implement is different opamps (Burr-Brown), and some more actions are on his usual to-do-list to get the best out of those. We'll see, and will report if there's interest.