Quincy,
If your comfort level requires that you use only new production tubes then that's what I think you should do. There's no sense in destroying your enjoyment of music with worry about what's in the equipment (and don't think I'm being sarcastic because I'm not!). I would ask you though, in these days of planned obsolescence, has improved quality control trumped the quest for the almighty dollar (or ruble as the case may be)? I believe that NOS tubes are, in general, better made than current production because people used to take pride in what they made. In addition, the tube sellers previously mentioned scrupulously test the NOS tubes they sell. I think I would worry more about putting an untested new-production tube in my amp than a NOS tube that HAS been tested but that's just me. In any case, you have a great preamp. Re-tube it and enjoy.
Dick
If your comfort level requires that you use only new production tubes then that's what I think you should do. There's no sense in destroying your enjoyment of music with worry about what's in the equipment (and don't think I'm being sarcastic because I'm not!). I would ask you though, in these days of planned obsolescence, has improved quality control trumped the quest for the almighty dollar (or ruble as the case may be)? I believe that NOS tubes are, in general, better made than current production because people used to take pride in what they made. In addition, the tube sellers previously mentioned scrupulously test the NOS tubes they sell. I think I would worry more about putting an untested new-production tube in my amp than a NOS tube that HAS been tested but that's just me. In any case, you have a great preamp. Re-tube it and enjoy.
Dick