Seeking tube 12AX7 recommendation for a Conrad-Johnson Premier 3

@arturos73 ,
Tubes branded as Hammond are good quality since they need to perform well in their organs.

According to the manual, the 5751s are used in both the line stage and phonostage as cathode followers and anode followers. They will have less influence on the sonics than the 12AX7 gain stage. But even cathode followers are worth rolling.

Tube complement:
V1,V2: 12AX7
V3,V4,V6,V7,V8: 5751
V5,V9: 5965

I like to pair a neutral tube with Mullards. RCA or GE blackplates are excellent tubes; open, smooth highs, but will add some warmth to the mids. IMO, RCA will add too much warmth.

My choice would be a Sylvania 5751 Triple Mica blackplate Premium. It’s a neutral and dynamic tube with airy highs. 
I see that Brent Jessee carries 1950s Tung Sol 5751s. Not as neutral as Sylvania, but open and dynamic.

Unfortunately Amperex does not offer a 5751, only a 12ax7 which CJ does not recommend as a substitute.

for 12ax7s, the PSVANE T-II. triple micas are my top choice now....just an extended musical sounding tube, that outperforms many NOS varieties.

Try a set, you will be pleasantly surprised.....

Give Brent Jesse a call. He can give you some good suggestions for 12AX7 tubes based on your what sound you prefer. Plus , he allows you to return any tubes not to your liking within 30 days of purchase..