Have there been any comparisons between the various 6L6 tubes? I've noticed the most common are the: 6L6GC, 6L6GB, & 6L6G. Coincidentally, these range from most to least expensive types, with the GC being far and away the most expensive.

Specifically, has anyone tried the 6L6G, both NOS and new re-issue. Will, I noticed your comments in your extensive review of the MK IV...no need to repeat here unless you have additional info to add.

Thanks to all who share their experiences.