amperex 6922 pq white label tubes

There are many variations of 6922/7308/6dj8/CCa/etc - even with white lettering and coming from Amperex. Cost is determined not only by matching and measurements, but also by wear, when they were made, etc. There are codes to indicate year and date - closely matched tubes should also be matched as to manufacturing dates, for example. I have several pairs of Amperex USA-made white label 6922 and have typically paid about 200usd per matched pair. The Ebay listed pair has seen significant wear despite the measurements. Like frogman, I have used PQ (premium quality) labeled O-getters; the sound is glorious. The AudioAsylum pair seem to be a better deal.

If you really want to get confused:

http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html#6DJ8

Then there’s the E188CC, E88CC, ECC88, CCa.
All the companies and countries where each were made,
plus all the changes to each over the years etc.

I would hold off on buying expensive tubes until you familiarize yourself with the variables, OR get advice from someone who knows the subject.
Save yourself from expensive mistakes and/or getting ripped-off.

About half of the "NOS" tubes I bought on ebay were not; some were not even marginally good when tested with a calibrated Hikock tub tester.  Stick w the known good dealers. Tomcy6 gave you a good place to start.

The acronym "NOS" (New Old Stock) is overly used by many, especially on eBay. This means the tube has never been used and tests at or above new values with no issues, shorts or gas, etc. Also, test results should be on a recognized tester that is calibrated. The tube should come in it’s original box, however sometimes that isn’t possible. Bulk pack tubes were packaged 100 to a single box. Many years ago I acquired some NOS Brimar tubes that were the remainder of a bulk pack and I did get that original large box. Many sellers label used tubes "NOS" if they test at or above new values, and most of the time what tester was used is never cited. This is very misleading, since it’s actually a used tube that has good test results if done on a recognized calibrated tester.

The term "matched" gets used loosely as well. Is the internal structure of each tube the same? Do the date codes match? How about test results, within 10%, 5%, etc and how does that relate to the sections of each tube, then to the pair? What type of tester was used and was it calibrated?

As others have said, it’s best to buy from a trusted seller. Otherwise before diving in, you need to know the water is clear or be able to detect just how cloudy it is. Sometimes on an extremely good deal that was just ever so slightly cloudy, I have taken a chance and everything was OK.

Now look back at those 2 pair of tubes and see if you can tell how different they really are.

Another reputable seller for new and NOS is TC Tubes. He also offers a testing service for your tubes with what is considered a reference tester, the Amplitrex.

Buy from one of the dealers on the list that tomcy6 provided.