I am using the VTM 200 monblocks, which replaced a Theta Dreadnaught. I felt that I gave up some bass going to the VTM's until I switched to the WE tubes. Even without breaking in the bass improved in both strength and articulation.
I put a 6550WE from RAM last night but, I only played one album so can't comment on any difference between it and the 6L6GC yet. Also, I don't expect the Svetlana 6550C tube from ARC until next week.
I do have a new 6550C tube that McIntosh uses but, I don't know if it is a Svetlana tube or not.
I am hoping a friend of mine will be comming by this weekend to help with some audio comparisons. I like to have a second set of ears when trying something new.