Jolida jd-502p

I would simply try them out. In virtually every instance that I rolled a 5751 in for a 12AX7 it worked. The different sonics may or may not appeal to you but I really like them. You may want to start with recent production NOS JAN 5751s from the 80s they shouldn't cost very much. It will give you an idea of what the better ones sound like. Have fun trying them out.

Try the GE TM gray plate 5751 from the 50s. The bass is prodigious in my experience and several friends as well. The Sylvania 2 mica Gray Plate 60s tube also has more bass than the RCA BP. As far as 12AX7s go you will prolly have to go with true Mullard Blackburn long plates "IF" you can get decent ones. They seem to emphasize bass. Failing that specific tube try any other older Mullard production.

Is the Sovtek the LPS variant. Those have a good reputation for being clean and quiet with high gain. They are not known for their Bass however which is kind of interesting. Since it is a phono pre I think you may just be better off with carefully selected current production tubes. NOS tubes are just not plentiful enough to find really quiet ones, with a couple of exceptions like Upscale, new production tubes can be screened in large batches and thus as a rule can be super quiet. If you can afford them the GL reissues are getting some good reviews for their tone. They should still be less than really good NOS. Jim McShane over on Audio Asylum can set you up with good ones.

I think Sovtek 12AX7 LPS tubes are "curent" production. In any event I consider them as current products. I know some are now speaking the virtues of Russian Old stock.

I can tell you from personal experience how much better a Jolida piece I once owned sounded after I rolled the tubes. At that time it was expensive but clearly not as bad as it is now for the better truly strong old stuff. I used Upscale Mil Spec Mullard CV 4004s. The impact on the sound was so great that I found it unlistenable without those tubes in place. That was before the advent of all of the reissue 12AX7s. I like them as well but still imagine that the improvement made by true Mullards is worth the investment. If you can somehow borrow a friends NOS tubes I think you will understand what I am saying. Ordinarily I would tell you to use 5751s but unfortunately the one and only circuit where they simply did not function was the Jolida.

Everyone likes what they like and if the Jolida makes you really happy why fight it. I say this because I imagine you have heard other makes of audio gear and are not naive. My own thoughts are that there are many better sounding pieces around including the EAR.
I use Chinese amps that are truly giant Killers. I honestly think their sound is about as good as it gets (in my system). They will never garner the respect of the mainstream audiophile community but I don't care and for the price paid they are simply ridiculously great.

Wolf don't you think "lurid" is a bit over the top. I like tube rolling mostly with old stock which has had it share of dissapointments. I do agree that the may be "pulls" and there is a flow of trading some which are indeed bad tubes until someone puts and end to it. If you can tolerate the chance issues, the rewards using old stock tubes can be enormous. I have a lot of fun listening for the differences the various tubes contribute. Some tubes are more reliable as old stock than others such as 6SN7s which are prone to microphonics but are usually good. The economics of rolling NOS/OS tubes are difficult to defend, but if you can afford it....
As far as power tubes go there is no sense in trying to find old stock that is still good, it is really almost a pure collectors market at this point.