I have several pairs of the Shuguang CV181-Z, the Shuguang CV181-T and the Psvane CV181-TII.
I prefer the Shuguang CV181-"Z" in everything I’ve tried so far. Best 6SN7 out there, IHMO. I found the "T" series to be just a tad to bright for my tastes. Most listeners would say they had more detail, but to my ears, that also means brighter.
I also really like the Sophia Electric 6SN7.
Info on the difference between the two companies:
Look at these new limited edition 6SN7 tubes! I might have to try a pair of these babies:
Thanks for the comments and info, guys. Yes, Mofi, these are the Zs and they seem to open and deepen with every passing hour. I contemplated the Sophias but took a chance with the Zs...glad I did.
And in case it's unclear, I have no vested interest in saying such things...I'm just kind of dumbfounded at how much of a difference one tube has made. It sounds like a completely different amplifier...
Discoveries as you experienced are what make audio such an interesting hobby. In addition to experimenting with driver tubes, there is a lot of potential improvement in trying a variety of audio grade fuses and audio grade wall A/C outlets.
Congratulations on the Black Treasures sounding so good in your system.