I agree that the GL KT-77 sounds great. If you liked the Svetlana EL-34 you might also want to try the Tesla E34L tube.
Tube recommendations for my Rogue Audio Cronus ...
First set of big tubes were the original stock Svetlana EL-34's. After three years, I replaced them with a beautiful sounding quad of Genelex Gold Lion KT-77's. It's now three and a half years with the GL's, and I need to start thinking of my next set. What are your ideas ?