Stickman,
I am not sure of the precise designation of the Amperex tubes. I got them free from a friend who has a vast store of tubes so I am relying on his judgment as to which are drop in replacements for the NOS RCA tubes suppli by the manufacturer of my phonostage. He gave me the pair I have, plus the pair of Telefunken ECC83s, Mullards, and GE 5751s. The only pair I had to buy myself was the Telefunken ECC803S (which easily costs more than all the others combined).
I am not sure of the precise designation of the Amperex tubes. I got them free from a friend who has a vast store of tubes so I am relying on his judgment as to which are drop in replacements for the NOS RCA tubes suppli by the manufacturer of my phonostage. He gave me the pair I have, plus the pair of Telefunken ECC83s, Mullards, and GE 5751s. The only pair I had to buy myself was the Telefunken ECC803S (which easily costs more than all the others combined).