Has anyone else tried 6F6 tubes in your mt? I have some RCA st shape from the 40s in mine now. They seem to get hotter than 6v6 with a little less volume, but they sound terrific. Being pretty new at this I can’t call out specific nuance of sound, but I’d say they are sweet sounding and well balanced across frequencies from bass to treble. I have listened to all types of music on them with excellent results but I especially like them for acoustic jazz (love that stand up bass coming through) and easy listening (Jackie Gleason). They sound good, look cool, and are cheap. What’s not to like?