The is a certain amount of variability in tubes made by any manufacturer.
Buying untested NOS tubes is a crap shoot. The most important and noticeable characteristic is noise. The best tubes have to be selected out by testing each individual tube. The only company I know of that does this is RAM Labs here http://www.tubeaudiostore.com/emission-labs.html
I use the Super Low Noise 6922's in my ARC phono amp and they are way quieter than the stock tubes and I mean Way Quieter. They are also super expensive @ $90. But you can choose Low Noise or Standard tubes. In a phono amp I think SLN tubes are a must. This is a difference you absolutely will hear. They have to test 100 tubes to get one SLN tube.
Mike
Buying untested NOS tubes is a crap shoot. The most important and noticeable characteristic is noise. The best tubes have to be selected out by testing each individual tube. The only company I know of that does this is RAM Labs here http://www.tubeaudiostore.com/emission-labs.html
I use the Super Low Noise 6922's in my ARC phono amp and they are way quieter than the stock tubes and I mean Way Quieter. They are also super expensive @ $90. But you can choose Low Noise or Standard tubes. In a phono amp I think SLN tubes are a must. This is a difference you absolutely will hear. They have to test 100 tubes to get one SLN tube.
Mike