So, I've had the Tung Sol 7236 in the power socket for a few days and I'm not sure I don't like the Sylvania 7236 better (I need to go back and re-listen for particulars on the sound) - but both are improvements over the stock power tube.
On the new Amperex driver tubes; I let them warm up for 15 minutes and started playing my favorite "new gear demo music", which is my SACD copy of Steely Dan's Aja. The sound difference from the stock driver tubes was interesting and not subtle.
I was blown away by the clarity in the lower mids / upper bass frequencies. I hate to sound like a 6moons reviewer, but I really heard a separation of instruments, a clarity and, well, sounds I haven't heard before from this disc (which I've listened to quite a bit).
The bad side, however, was the a veiled sound to the treble frequencies (I'm not experienced enough to guess the frequency range), but the highs were muted - at first. I let it go, listened to the entire album, then switched to the SACD of Pink Floyd's DSotM and listened to that in it's entirety. By the end of that disk, the highs started to expose themselves more. Then I moved on to Wish You Were Here and by the end of that disc, I wasn't aware of the muted highs.
I am wondering if my sensitivity to the lower mids / upper bass was due to the muting of the highs, at the start. It was kinda cool to experience, though - it was like hearing a familiar disc for the first time.
Anyway, I am going to have another listen tonight and see how things unfold with some jazz and classical favorites. Overall, however, a substantial improvement over the stock tubes which I was not expecting (to be honest, I expected them to sound the same).
Next on deck for appraisal: the Telefunken E188CC/7308 drivers: