For the 6CA7 (EL-34) tube in a classic Marantz, my first choice would be NOS Mullard XF1 or XF2.
If you prefer current production tubes and want to save some bucks, the Tesla E34L is a excellent value as well as the Electro Harmonix EL34 or Winged C EL34 (which is the ORIGINAL Svetlana).
I have not tested the new reissue "Mullard" EL34 sold by New Sensor. I do know this new "Mullard" is built on the same production line along side the Sovtek EL34 (Reflektor factory, Russia), so I suspect they are very similar but with different cosmetics.
For the 12AX7, it's easier. The new Groove Tube 12AX7 and Sovtek 12AX7LPS are both amazingly good, especially considering what they cost.
I have not experimented with EL84 (6BQ5) so I won't make any recommendations. Good luck !
If you prefer current production tubes and want to save some bucks, the Tesla E34L is a excellent value as well as the Electro Harmonix EL34 or Winged C EL34 (which is the ORIGINAL Svetlana).
I have not tested the new reissue "Mullard" EL34 sold by New Sensor. I do know this new "Mullard" is built on the same production line along side the Sovtek EL34 (Reflektor factory, Russia), so I suspect they are very similar but with different cosmetics.
For the 12AX7, it's easier. The new Groove Tube 12AX7 and Sovtek 12AX7LPS are both amazingly good, especially considering what they cost.
I have not experimented with EL84 (6BQ5) so I won't make any recommendations. Good luck !