While I like many genres of music, jazz is my favorite and I spend a lot of time listening to it. Maybe smooth isn't the best choice of words, but when listening to jazz, everything sounds just right with the Sophia 6SL7. Not edgy unless the music is edgy (such as a particular sax solo).
Here are a few pictures of my Sylvania 6SL7. It probably looks like all the rest. It does sound as if transients from snare hits have a bit more snap, for example. 85% of my listening has the Sophia in the amp, and 10% the 1952 Sylvania and 5% everything else. I agree that the Sophia is one great 6SL7 for most of my listening. I bought several from the same production run.
I haven't had much time to try tubes lately and also my GS-X came in which takes some time experimenting with balanced as well.
I'm currently still playinf iwt the Philips ECG JAN 6SL7WGT I got from Craig which is so much better than the stock Tung-Sol 6SL7GT.
Have you tried a TS 6SU7 yet and if so which type? How did it compare to the Sophia?