I have a 275 VI. I was disappointed with the sound using stock tubes. Make a long story short, I finally ended with winged C 6550s, Sylvania at7s, and telefunken ax7s. After these changes the amp sounds right with excellent, non cloudy bass, excellent detail, and very fine imaging. I have gotten the impression that some owners of the newer 275s are disappointed, but they might not be with better tubes.
