NOS Tubes - Ecstasy or Agony

I have been running tube amps for many years and have built a number of SETs and other tube amps, kit's mostly.  My main power tubes have been 2A3's and 300bs and I have used mostly new manufacture tubes including JJ's and EML 300b's (great tube btw).  I did use NOS driver tubes and headphone amp tubes.  Never really had a problem.

I just transitioned to a Don Sach's 6sn7 based preamp and McCormack SS power amp.  The preamp is very nice and sounds great with Shugang tubes. Of course, I wanted to try some NOS tubes, went online and did my research.  Now the DS2 is a great preamp, the drawback is it uses 4 6sn7s and so I need to get pairs.  Would  have love to get my hands on the Dehavilland, uses one tube!

First Pair - I ordered some Sylvania's from TC Tubes. Advertised as 50's vintage, ,when I received  them they were marked 60's. Hmmm.  So I tried them and they sounded pretty darn good except after a couple hours one of them developed a high pitched hum, like a florescent bulb. So I sent them back.  

Second Pair - ordered from Brent Jesse - has a good rep online and a really informative website.  Received them and one was dead on arrival, they were also clearly of different construction. So they are going back.

Next will try Andy at Vintage Tubes Services, he also has a solid  reputation so hopefully I can get something that works.

I am curious what experiences others have had. Maybe its COVID, or are these dealers just unreliable, or is just 6sn7's?  Really thought I could just buy some NOS tubes and experiment, I can't even get two to work.

I don't really want to disparage these dealers but I do think all the claims of testing are maybe overblown.
In the past, I have had great success with NOS tubes. But recently, have had consistent failures of 12AT7s. Bought 3 pair from,I thought a reliable source.
Have made a note of Brant Jesse. I have been told that NOS, especially for a preamp, are rarely quiet enough. Normal testing only reveals the main functions of a tube and not how it will sound. Believe a complete test must include actually putting the tube in a component. And hearing it for several minutes. I doubt that many or any tube sellers will do this.
Manufacturers may do this for their stock tubes. But, I think, most will use cheap new stock tubes that they buy by the hundreds in order to find the good ones. Am getting a new preamp with 18 tubes: 8 12AT7s and 10 6SN7s! They will all be new, all Chinese I think, tubes that were sorted out and “completely” tested.
Maybe Brent can supply tubes sorted. I am very hesitant to replace the stock tubes. Psvane offers some tubes that have been sorted out from many. Don’t know if they do a complete test but they do charge a lot for these “premium” tubes.
Brent and Andy both grade tubes based on microphonics for line stage use vs phono.  

And I want to say, Brent has been outstanding on follow up and helping me get a good set of 6sn7s for my DS-2.  I feel the extra effort is worth it. I have a nice Pass Labs passive pre, love it, but it doesn't compete for musicality with my tube pre.
Two of the most satisfying changes to my system are attributable to NOS tubes.   The first was a NOS Mullard in the power supply of a Modwright 36.5 linestage. My jaw dropped.  The second was trying NOS Sylvania and Ken Rad 6Sn7's in a VAC 200 IQ power amp.  The Sylvania were amazingly transparent. The Ken Rad's were full bodied, clear, wide bandwidth and my final choice.

What I like about this is that dramatic changes are available for a few hundred dollars, you can deep dive into researching the subject, you can gain access to some of the best ever made, and what you get probably won't depreciate. It lets you be a hands-on hobbyist again as audio increasingly moves to streaming (for good reasons) with locked-box appliances.  Yeah, there's some current obsession with getting digital data to the DAC, but whether real or imagined, that's complete solvable beyond further improvement, but I digress. 

Shout out to Brent, Vintage Tube, and catluck.

I have purchased several singles and matched pairs of NOS from Upscale Audio. All have been just as advertised and no DOA's. I personally don't believe there are many, if any suppliers who do the kind of comprehensive testing that Upscale does on the tubes they sell. And no, I am not a paid spokesperson, just a very satisfied customer.
NOS...."New Old Stock", only 3 weeks old since demand has fallen off of late....

"Hey, Lorraine? These boxes aren’t ’aged’ enough to be ’believable’. Can you smudge them up a bit more?"

Does anyone truly believe there are stashes of old tubes out there Still?

If so....I've got some lake bottom property next to the Brooklyn Bridge to put up an 'old condo' on.....