For Tube Folks...

Even new tubes are tested by resellers before they're sold. A while back, I bought four Telefunken military grade tubes for a radio multiplex. I got them on eBay and the seller was, I believe, an old Ham Radio Operator and these were from his own collection. He had an Amplitrex tester and was very transparent about the whole process. I just had to make the decision on whether or not to trust him and now, I'm really glad I did. But this was long ago, way before the insane prices that we now see for NOS Telefunkens. 

Currently I'm in the market for a Linlai E 6sn7. I've decided that there are some new tube manufacturers that offer a better value than those highly coveted Western Electric, etc... Plus when you by a new tube, it comes with a warranty.

Use the new tube, it's the way to go. You are trouble free.Tung Sol is good enough for me and it's lifespan is very long.

@ghdprentice   once I went to your pictures - it appears you are quite the photographer. Thoroughly enjoyed some of your city shots after the tubes.

You know how to make a camera sing !

@firberger 

Thank you.

If you want really well matched output tubes you need to burn them in for awhile and retest. They will drift around a bit when they are new. Unless you are curve tracing, you will need to test under the conditions of your amp. Fixed bias amps usually allow for adjusting the balance of the bias current in the output transformer so perfect match is then not necessary. With cathode bias you will want to be closer. If a tube is going to fail from a defect, it will most likely fail in the first 100 hours. Also, in my experience it takes tubes 50-100 hours before they sound the best. For me it doesn't make sense trying to locate matched NOS output tubes. I would suggest finding current production output tubes that you like and stock up. And if the dealer burns them in first before testing I would consider that a good thing.

As for boxes, tubes from the 1950's & 60's the boxes used cardboard with a high acid residue that over time turns them a brownish color and makes the cardboard very brittle. Just opening the box to test can damage the packaging.