Just got the Sophia Electric Princess mesh-plate rectifier I ordered from Macedanian Hero. MH, I can't believe how fast it got here - thanks!
After only a few minutes, this is EXACTLY what i was hoping it would be. It widened the sound stage, tightened the bass up and made it more articulate, and sped things up a tad all at the same time compared to my Mullard GZ37. I was looking for a nice middle ground between my GZ34 and GZ37 and instead got a complete improvement over both. It goes great with my Sylvania chrome top 6SN7, which are very nice and have nice lush mids.
I'll have to try my Tung Sol 6F8G again tonight with the princess now. Using the Mullard GZ37 and GZ34, I ended up preferring the Sylvania 6SN7. Be interesting to try again with the Princess this time since the combo has a lot to do with how a given tube sounds.