Krell's first foray into variable bias, Sustained Plateau Bias, was a fucking horror show. I traded in a fantastic KSA-50 Mk II (with confirmed boards from KSA-100 as they were close to end of manufacturer life, so shared some parts), and got the KSA-50S. BIG drop in sound quality, had major seller's remorse on that one.
They got it better in later lines, but that first one sucked. I'd hope others like Dussun wouldn't make similar mistakes.