As Yogi and George have already stated, you will not get any more gain from another 12Axx tube type. The circuit was designed around a 12AX7, so you're best to stay with that tube. You can likely improve the sound quality though with a different tube, especially if you have the factory supplied EH or run-of-the-mill Chinese tubes in there now. I (personally) do not like Mullards in anything made by Cary...too soft, veiled, and sluggish. The RCA's George mentions are a really good prospect, but a genuine NOS pair will set you back some money. The new-manufacture Gold Lions are very good, not to the level of a black plate RCA, but much better than the factory tubes and won't cost you an arm and a leg. In any event, if you decide to try different tubes, I would highly recommend you buy replacements from a trustworthy, established tube vendor that carefully screens and tests the tubes for noise, as that will be a critical parameter for the phono gain application.
Tubes for cary preamp Phono Section?
Hi everyone I have recently purchased a New Rega RP8 turntable with a Ortofon Bronze cartridge and i am running it through my cary SLP-98P preamp and Cary Cad120s power amp with great results. Now I had a person suggest. That I can change the 12AX7 tubes from the stock ones to a different type to get more gain in the phono section of the amp. Has anyone tried this and if so which tubes did you use and any recommendation on brand? Also what where the results?