6SN7 tube GTA vrs GTB

The GTB was developed to handle 450 volts on the plates the earlier GTAs and GTs should really be biased down to 350 Volts. As for sound Only your ears will count. That said the GTB tends toward the warmer side and work well in an analytic system otherwise. The Old Stock 6SN7s are reasonably priced unlike everything else for audio and not including obscure Ham tubes. I would try a few different 6SN7s don't omit the GTs.
The GT are favored by many including me, the WGT is a tougher mil spec variant that I like as well. The Gts are popular and the demand is relatively high the good news is the the supply is enormous, thus fair pries. I have read that the 6SN7 was favored by the engineers due to their linear behavior. They were widely applied and many "millions" are out there. There is excessive demand for some of them, they are good no doubt, but the tube dejour are royally expensive.

Rodmann,
You happen to prefer the most commonly sought after royally expensive 6SN7s. I own three pairs of CTL Tung Sol RPs I really do. I have a few Ws as well. Both of those cost about $400-500 a pair. The market is starved for them. I used them for a while in my preamp and concurr they are superb no arguement there. I think that less coslty alternatives serve me almost as well. I have a very big collection so I change them around from time to time. The only tube I never really sought after was the 5962 I have 2 pairs and gave away 2 more Yes I did. The 52 Bad boys were also produced in late 51 and early 53. Not all Sylvania 52 GTs are bad boys btw. The WGT is a very fast tube that is neutral enough and if you look carefully resemble Ws in their construction. They are all short bottles which are not considered dreadful by the market.
As far as W's go, I have tall and short the tall wins but I wouldn't go so far as to call the shorts to be avoided like the plague. What did you find so aweful about them.
In any event the RCA VT231 in Grey Glass are well liked for their fluid,sweet, some say lush sound. The latter RCAs are all servicable but not outstanding. The Brimar GTs are quite good but a tad to euphonic I am sure for some. I don't have any other Euro N7. The 2 Raytheon types, the Hytron, and CBS, the Ken rads non bad Boy CHS vt231 Sylvanias, the various GTBs. All of them have very characteristic sonic signatures no they are not those Tung Sol GT RPs not as great as the W's.
Those less than great tubes, to certain people, though are not royally expensive and provide plenty of other great tubes to try without resorting to the acklnowledged no brainer top picks of Tung Sol Round Plates.
Yes TS RPs are truly excellent as are the W's. If you can't spend $500 for your N7s the truly smart buyer will find a tube that suites them for less. There is no point to keep pounding at the obvious. It's akin to saying that the best turntable is the Galiber or the Walker -we all know OK. Anybody want the best tubes I have mentioned for free? What's this? everyone who owns a N7 amp wants them, Geeze I would never have guessed. Sorry I don't have enough to go around Oh Well.

Well I am happy to have finally sorted through enough N7s to have all of the TS RPs in one tray which has a bunch of other fairly good to superb ,no not the TS level tubes.The bad news or good news depending how you see it is that this is not even close to all of them.I have atray of RCAs the good the medium and the not so great IMHO. One tube a l only single is just called a CCA not related at all to 6922. It is definately an RCA with a CRC marking.
I have had the experience of dead silent tubes become microphonic it is in the non reinforced architechture. Curiously I never hear the whine or ringing people describe. I do have a resolving analytic system which will show warts and all.
The dealer cannot promise that even the most rigid will stay non micrphonic. What they do is better matching for gain etc and intertriode imbalance. These are like any twin triode one can be more than 10% different than the other. This does have a measurable effect but again you have to be looking for it. I know because I have had pairs that weren't close and used a SPL meter to measure the difference it is there, but not obvious.