@lowrider57 UK-6SN7, seems like it would be worth a go. I did read once the clear UK version might be more neutral, less lush, compared to the gray coated CV181-IIs like I have now. And, we know the sound changes in different amp circuits, amps. It was a flip of a coin to try either for me, and a friend had good luck with his gray glass output tubes in an older Jolida, KT88s, running them for 2yrs solid now with no issues, so I tried the gray glass PSV CV181s next. Yours may vary.
PSV-181s: A litte more detail is coming through now after 75hrs on the PSV CV181s, yet they are definitely a tad more lush at the same time. A little more of the highs rolled off [slightly, not bad] compared to my vintage sylvanias or the TJFM. I like them, super easy to listen to for most content I listen to online. Keeping them in place for now. Wanna see what happens at 200hrs. Storing others.
AN-PSV: For a while there the AN use of PSVANE tubes was kept on the down-low. My local dealer was telling me two years ago before the pandemic that Peter [@AN] has his own spec on the tubes made for them, fwiw. Not sure how much different they could be beyond a label change. Would have to buy a pair to compare native PSV vs AN versions of the tubes in an actual AN amp I guess.