Samzx12:
I went back and reread your post. And before I add more to this thread, I just want to say that I agree with our Red Wings fan from Detroit: the choice of tubes is very personal.
I was going to follow-up my first post with another saying that I should have asked you what you were trying to achieve, but you did say that, "I want a little more transparency or pop yet retaining overall smoothness and good bass."
I would have said that if you were trying to brighten up a dark sounding system, or add more air and sparkle, go with the Sylvanias in the 6SN7 position. If you were not trying to enhance that effect in your system, try the RCAs - they offer a good balance of smoothness and bass, and you dont have to spend the $$$ on the 5692s to get those qualities. But either way, make sure you get a 6SN7 with low microphonics.
For the 12AX7, the Telefunkens are more dynamic than the 5751s, but I went with the 5751 because I liked their musicality - and they lowered the noise floor on my system even further. But your use of the word pop would tend to make me think Telefunken
but my experience is probably more limited than the others contributing to this thread and I would not discount differing opinions. But in my system, no matter how much I really wanted to like the Telefunkens, I kept coming back to the 5751 and relaxing and listening to music with a smile on my face.
But my system was already very transparent and detailed, so that's why I have been moving away from tubes that are usually described as bringing out "air" and "sparkle"... my system doesn't need help in that regard. So for me, the RCAs have been a really nice balance. And like I said in my first post, the Sylvanias in my system were unacceptable, but for another guy that comes into our local shop and whose system had a darker sound, the Sylvanias worked out really well.