Primaluna - Rolling pre tubes question...

I think that Kevin Deal/Upscale would be the first place I would buy upgraded 12AU7s from, since they should know their own amps. You might just call them and ask where the tubes do the most good.

I agree with them as well the power tubes have a greater impact on the sound than the pre tubes. I answered thinking you were set on your power tubes.
In general I am quite fond of the Gold Lion tubes now available, but I leave to you to decide which you want to try.

Well now that you do indeed have your power tubes of choice. What sound are you hoping to get from the small signal tubes. That will be a tremendous help.
Since you didn't like the Gold Lions which lean towards warmth I don't think that British tubes would be what you want, but you may want to balance out your Psvanes with them. Please provide more info. Otherwise if you simply want strong clean transparent sound German tubes (e.g. Telefunken ??Siemens not sure they made a 12AU7) may be the answer albeit expensive.
My all time favorite are early 60s, late 50s Amperex which I think do it all, but are being counterfeited and subbed allover for big $$. And don't fall for the low noise 7316 variant if it not made by Amperex,(and often labeled a computer company) these are truly special but people are calling anything they want a 7316. They must come from Heerlen Holland with the right triangle and ctl with a # in the acid etch . Otherwise just look for Amperex 12AU7s to make it simple all have the Philips seamed top. The real Amperex 12AU7s are expensive the 7316s even a bit more. Sif you wanted a cheap option this isn't it.

Yes there are classically warm British tubes like the Mullard ECC82, the Philips Miniwatt, Mazda,and even Valvo (which is as likely to be German so be careful, etch code is your ally) and the Mullard Mil Spec 4003.Another British tube that glides under the radar that is the more neutral sub made by Brimar the 13D5. I am sure you can find Mullards to try., but if you didn't like the reissue Gold Lions not sure you would like these either. Did you try the small Gold Lions? I forget but does the treasure series include some of the pre amp tubes?

I never invested in a pair of the fancy recent treasure or Psvane tubes believing that they were marketing ploy for Shuguang or Sino brand tubes in a pretty bottle. I had liked the Sino 12AX7 9C version. I think that is it -it is so long since I had used them. They made them and then stopped and just make the 12AX7 8 B. Beats me but I see that Uncle Kevin (Upscale) has made a few comments, I would trust him as I had advised right away.