EL34 & 6L6 characteristics

Saki,
I used the Shuguang Black Treasure 6CA7 in my Primaluna Dialogue One. It sounds to me to combine the best attributes of my NOS Reflector 6n3ce (6L6) and my NOS RFT Siemens EL34. Better detail and air, yet full, a drop of warmth, increase of quality bass. Generally all around better in my system. The Simens are also good performers. You might also like the Bugle Boy 12au7s in combo with Sylvania 5751 3 Mica Black Plates in the Primaluna. I know I like them a lot.

Saki,
The Shuguang Black Treasure 6CA7 is available in quantity from Rachel at Grant Fidelity. Likely about $300 per quad. Grant stands behind everything they sell. I also believe Trelja here, at Audiogon sells this tube. The RFT Siemens EL34 is harder to get and can be costly. I paid about $200 for a matched pair from Brent Jesse and $150 that matched well with the Jesse tubes from a friend.
I have also used the Mullards, very nice in 12ax7 position. I forgot to mention mention that I used the Gold Lion KT77s. Again, the Shuguang Black Treasure did it for me in both the Primaluna as well as my Coincident Dynamo 34SE. Best

I really like the Shuguang EL34B. That surprised me. I liked them better in my Coincident Dynamo 34SE than some NOS that shall remain nameless. I am really enjoying the Shuguang Black Treasure 6CA7 even more so.

As I said above they shall remain nameless.