Bit of a delay, but coming back to this, I had some time and proper mindset and all to sit down and swap tubes for a bit out of curiosity. However, I have forgotten virtually everything I learned about how to properly analyze the sound, lol. What I can tell you in particular is the Golden Lion seemed to have more detail as in I could hear finer parts of several songs better with it. Probably emphasizing certain specific frequency ranges or something, but I couldn't tell you what specifically they are if it is (somewhere in the mids I guess?) I popped in the Tung Sol and the Magnavox and of the two the Tung Sol did seem to have a more enjoyable sound than the Magnavox, though the difference was a bit too subtle for me to describe as exactly as I would like. However, it's only fair to note that the Magnavox was very very used even at the time I got it and someday I probably need to track down a NOS or at least one in better shape (I'm pretty sure it was an extremely used tube before I got it which might partially explain why they accepted a low-ball offer.) It has a burn at the top (not the gas absorption material, but an actual burn) and the metals seem to have changed color a bit inside (a sign of reaching relatively high temperatures,) so clearly it was well used before I got it. (There is also a crack in the plastic, but not the glass, so that presumably doesn't matter.) It could be the Magnavox is actually a lot better if its condition is better. Someday I'll find out I guess, but sadly that's not today. I do think the Tung Sol probably still is overall better though.
Of course, it could be the biggest differences of those two really show up when there is also some current drain. It's too bad the Vali 2 doesn't simulate just a bit of current drain (a resistor or something maybe?) to bring their power profiles a bit closer to what they expect. I'd be curious to compare the difference with a setup that draws more like what is expected of a tube. Someday when money isn't so tight I may try going full tube amp and see first-hand. (But then with headphones like these a hybrid may still be the best compliment anyway.)