I did a similar trial w/ my AtmaSphers MA1s. I had all EH 6SN7s in them for about a year or more. I replaced the 3 middle tubes (considered the most critical, sonically)with TS Reissues. My first impression after letting them burn in for about 20 hours was that they were much more dynamic and tighter in the bass. I began to wonder, though, how much of the effect was due tot comparing them to tubes that had many more hours on them. So I bought some new EH tubes, and tried them out. I put the new EH in one amp, left the TS in the other, and played them for a few weeks before listening cpomparitively. What I heard was that the 2 tube types were extremeely similar. I could not tell much, if any difference, although I desperately wanted to. If anything, I thought the TS were slightly more forward in the midrange, which in my system was not a good thing. I think I put the old EH in for a bit, and concluded that the new tubes sounded very much like the old EH; in other words, the initial improvement I heard with the new TS wore off in rather short order with use. I wanted to spend some more time with these comparisons, since I bought the new EH just for this purpose, but I got distracted with chewcking out some new source components. Ultimately, I got bored with trying to hear the differences between the tubes, because they seemed so slight, once they all had some serious time on them. I would like to go back and compare again, but I'm sick of listening to equipment, and have been enjoying listening to music for a while. I'd love to hear any other opinions on this, especially after your tubes burn in for a while Ait. It's pretty cool that you can vary the gain on your input tubes like that to tailor the sound.