I expect many of you will already know all this stuff I'm writing below. Some of you might even have the facts/chronology in your head better than I do. I share it here for those who *might not* have *been there at the time* and for whom it might prove informative.
Regarding the CV-181 terminology used with respect to 6SN7 tubes. Way back when - like a couple years ago when those tubes first came out - every site, every ad I saw for them stated specifically that they CV-181 nomenclature was incorrect and that they should only be regarded as drop-in replacements for 6SN7 tubes. And virtually all ads and sites were scratching their heads at the choice of the CV-181 name for these tubes.
Having said that, the "Black Treasure" CV-181 tubes were very highly regarded. IIRC they were Shuguang branded until Grant Fidelity, in Canada, came of with the Psvane brand name. I think that was the result of collaboration with the marketing folks at Shuguang.
The so-called WE6SN7plus tubes, specifically the ones with the orange metal base and the extremely tall bottle, were very, very highly regarded. After they'd been in production for a while there was, IIRC, a fire at the Shuguang plant and they shut down production.
Another page turned and, apparently, the top engineers who had been involved in the Psvane venture left to form Linlai.
Apparently the Linlai production tubes are well regarded. I have not tried any of them, being content with my old US production 6SN7s and my JJ 300b tubes.