This year they updated both the Krankenstein and Rev1 with new transformers and 6550 (KT88) tubes. I must say I'm curious. I liked the Rev1 to begin with but I REALLY want to try out one of the new ones! I also heard today from a very reliable source that the new Krankenstein is KILLER! This came from a guy that knows tone, is very experienced, owns SEVERAL great amps, and was a previous Krank hater. He now owns it and it's his new favorite amp.