How do the Electro Harmonix 6sn7's sound?

Jppenn, Do yourself a favor, you don't have a huge tube roll here. Don't mess with the non NOS tubes. It's a waste of time and money. Go for the old valves. Experiment a little. For me all of the Sylvania's the W(40's), GT & GTA(50's), and GTB(50's to 60's) are wonderful and are far superior to the current manufactured tubes such as the Electro Harmonix you mentioned. Sylvania has it all sonically, few could argue. The Sylvania 6SN7 IMHO is the finest American tube ever made, bar none. In general they are progressively better the further back you go by some measure but that said the GTB's have smoked any current production tube I've ever heard in my applications. Just keep in mind that the price goes up with the scarcity and age of the tube. I run ten of them in my Atma-Sphere OTL MA-1 amps and have never heard these amps sound better. I have a friend that runs them in his phono amp and loves them.
Happy Listening!

I just picked up a set of Sylvania 6SN7GTB's from Andy Bowman of Vintage Tube Services for thirty-six dollars each and they were tested as new by him. Very nice stuff for the money and Andy is the best vintage tube guy I know.

Dgclark0007, To answer you on the thread and we can talk more about it off line I use both Sovtek 6AS7G's or Svetlana 6H13C with the flying "C" for my power tubes. Cheers!