Appreciate the replies! I think under the right circumstances a lot of the views expressed could be valid. Similarly, I'd like to venture into viewpoints that don't really get much expression in tube forums.
RE Chinese reliability. This cracks me up, because false information is constantly spread on the internet and becomes accepted. If you look at publications from the height of 6sn7 tube production the failure rates are terrible.
https://ethw.org/First-Hand:Tube_Manufacturing_at_Sylvania First paragraph, scrap rates 30-40%!!!! Sure they brought it down over time, but to what level? Many manufacturers ran the same equipment for decades, which would inherently limit quality improvements. Also, tubes are inherently fragile, and rely on very narrow tolerances to decide if they live or die. Hey, so do light bulbs! The thing is, you don't see the NOS scrap rate as a tube buyer because all the scrap has been invisibly filtered out by time (handling, transport, less than ideal conditions), and tube screeners. Does anyone really believe that the 70 year old tube available today is even remotely representative of historic production? Check out any forum of old timers who remember regularly popping down to the hardware store to pickup another tube because the last went bad or failed.
If anything, operating in low margin, internationally competitive markets for a tiny niche market would necessitate low scrap rates and tighter tolerances for modern tubes. People can gripe about their bad experiences, but it isn't representative. I have found a few bad mentions for the Linlai e6sn7 tubes, and many resounding thumbs up. Current serial numbers are ~25,000+. From a manufacturing perspective for a niche market, those are enviable numbers. Obviously we don't know the actual numbers and warranty returns, but what info is available points to the opposite conclusion. Psvane is obviously much larger, and will have more individual instances of people reporting failures.
As far as branding and screening goes, this is common practice in open market manufacturing and regional targeting. Whether there is actually a difference or not is the question. Some retailers say there is, others are very careful to say a lot of things and make no claims whatsoever. NONE of them actually provide actual measurements in comparison to the ideal 6SN7 and prove that their marketing claims reflect reality. There is nothing proprietary about what they do, and contract agreements would protect their access to supply if it was known. I am highly skeptical that there is any merit to the process. Much of what is claimed about the screening tolerances would point to longer operation of the tube (if I am reading historical tube design info correctly), but given that tubes just sound worse over time regardless, I would rather skip the astounding markup and marketing costs in favor of having double the tubes. But hey, people make purchase decisions according to their emotional needs all the time. If that is what works for them I'm not going to complain and neither is the business. Their goal is to extract the most money possible for their investment and time, and the market react accordingly to what it perceives as value.
I have followed the top recommended NOS tube sellers over the last year, comparing inventory levels and pricing. They are out of stock on nearly everything worth pursuing, and the pricing indicates the market is dried up. $200- 800 a pair, if they ever come back in stock? Look back to early 2000's forums and you will see that the most consistently recommended tubes were becoming hard to find and pricey. Sure with a quality rebuilt tester that has been professionally calibrated ($1500 ish for a full featured hickok?), multiple purchases (and losses reselling), and the cost of your time, you could find nice sets of NOS tubes from private sellers. Be honest though, this would be at great expense. Not an argument against pursuing NOS tubes, but it probably isn't worth it for most people to even consider. The micro economics indicates the market has been cleaned out for quite some time, and it isn't a great place to be spending money without context.
