Phono preamp tube rolling.

Lewm is right, tube rolling will drive you crazy. The most important characteristic for a phono preamp is low noise. Both RAM Labs and Upscale Audio test their tubes. It is better to spend more on the super low noise tubes or Kevin's stash which are also superior in other parameters. Tubes are quite variable in these regards. With tube testing you know what you are getting. It's a good investment as preamp tubes can last a very long time. I change my phono stage tubes every 5 years whether they need it or not and my unit stays lit 24/7 (when I have a turntable:-(

Yes, tubes age at different rates. It is however my experience that tubes that start off low noise continue to have relatively low noise over their life span. I undoubtedly change tubes prematurely. I change my oil prematurely also. Makes me feel better.

When I first got Super low noise 6922's from RAM Labs I was flabbergasted at how much quieter they were than the stock tubes. This is an ARC phono stage! Every set that I have gotten have been just as quiet. They are so quiet that with the volume cranked to the max I have to put my head up against the speaker to hear anything.

surfmuz, it is always best to use the specified tube.