Got the Brimar CV 4004 today- it is a variant of 12AX7 that went in to V2. Some one this thread had mentioned a Mullard CV 4004 for V2 being a good choice as well. The Brimar lowered my noise floor and increased the detail, but it did not match the telefuncan 12AX7 that I had in V3. My current recommendation based on my tube rolling with this modded EAR 834P:
I now have Valvo 6201 blue print in V1 ( 6201 is a 12AT7 variant), Brimar CV 4004 dated 1962 in V2, and Sylvania Gold Brand gold pin 6201 in V3. This is my best combination yet! I collected quite a few high end tubes on this journey, but should get many hours of vinyl/ tube pleasure.
I now have Valvo 6201 blue print in V1 ( 6201 is a 12AT7 variant), Brimar CV 4004 dated 1962 in V2, and Sylvania Gold Brand gold pin 6201 in V3. This is my best combination yet! I collected quite a few high end tubes on this journey, but should get many hours of vinyl/ tube pleasure.