Old Legendary tubes vs New Kids on the block Amperex/Siemens/Tele vs Psvane/TAD/Shugaung

Posting this on amps board, as pre tubes can make quite a dif on the amp ound. 
I just sent off all my oldstock tubes to a  guy who will sell them for me on ebay,,I am going all ~New kids on the block~ pre tubes. 
I am saying goodbye to my fav~ Amperex BB.s 
The only old stock i am keeping are the 2 tall bottle SQ Philips EC180's which will go in the AU section of the Defy,,i love the cool looking tall bottle of the EC180,'s, But i also bought some Psvane Au's , a sthey look quite impressive with taht double plate at the top,,,Will add some TAD AU's also on wish list, they also have thae cool looking double plate./high tech components.
I will roll the 3 labs, and see wich has the finer resolution/soundstage.
The 4 AX's will have to be the Shugaung, Maybe later on will add the TAD.
The cayin cd17 takes 4 6922's, for those I will go TAD, as they have the cool looking double plates. 
Which brings up this Q...will the old legends hold their top $ prices going forward, as folks begin cking out the new labs offerings, 
I've not heard any of the new, as yet, I have the AU's/AX's arriving later this week. Since i sent all my old stock au/ax's off, can't compare to these new labs. Only compare from what i reacll the Defy sounding like  with Old stock. 
However as you guys know i still have that cheap chinese clone which is crippling the Defy's performance. 
The cayin SC6 is still a ways off, so a  true compare could only be made at that time. 
The cayin has 4 AU's, will roll both TAD and Psvane T series AU's. , Psvane has a  new ax out called T series,,,I will buy both the Psvane and the TAD, see which comes out for high resolution of fq's. 
Have you guys heard any of these newer labs, vs the old legends. 
On the power tubes, I have EH KT90's and also chinese KT88's i bought cheap off ebay,,so will roll those  when the front tubes arrive. 
Will not rebias the amp,,it will be a  justa  shortb 10 minute testing.
If I like the 88's over the EH90's,,I will add the Psvane KT88 C version to wish list, The C version is the newer KT88 from Psvane called the Classic 88, the older version is called the hifi 88. 
I will post notes over the comming year as these tests will be ongoing during the year 2020. 
What say you about these new kids on the block?
Someone noted above that all new tube audio equipment comes with current production tubes. That is because if the manufacturer used NOS tubes the unit would cost hundreds more than it does. The only tubes currently being made are either from Russia or China. My amp came with 8 tubes made by Electro Harmonics; they probably cost the amp maker maybe 80 dollars. The 8 tubes I now have in my amp cost me about a thousand dollars. And some of them are nearly as old as me; 65 years. Those 8 tubes have been in the amp for over seven years. 
I just wanted to say that I think this is a great thread. Here's the reason, and that is that there is a very wide range of experience with tubes on this board. And this is a good opportunity for those who have more experience to shed their no kidding experience with those of us who might be relatively new to tubes. 50 years ago I was running an eico st-70. Then about 40 years ago I switched over to a luxman solid-state. Then about 30 years ago I switched over to Naim equipment. Then there was a time about 15 years ago when I switched over to a dynaco st-70. But I was using a solid-state preamp. Now I'm using the supratek Cortese all tube preamp. And I think it's totally awesome. But I don't have much experience with tubes, or rolling tubes. It's something I'm fascinated with but I don't really have the experience that some of you guys have. So This Thread is really good for somebody whose relative newcomer like me.
Supratek Cortese,with a pre amp of that caliber only the very best vintage will do.I mean tubes not wine.
well folks, the shoot out has commenced. 
Just preliminary testing has shown
The Shugaung New T Series AX ( $75/pair)   *New Kids On the Block* have not stood up to 
The Sylvania AX's have not stood up to the 
1 Sylvania +  1 RCA tall black plate.

(waiting for a  bunch of RCA's to arrive early next week , and employ a  pair in one channel)

I am in the middle of this shootout twix RCA Black plates and Philips Mini watts. 
can not complete testing until another RCA arrives.
From preliminary testing,
The RCA's will beat out the Philips,,I have 7 pairs of Philips Miniwatts, and will test 3 pairs vs a  full pair of RCA's, 
Will also make sure the testing is fair, by switching the 2 tubes, to left and right channel, just in case the recordings are UNBLANCED, 
My hunch tells me the RCA Black Plates will top the Philips (= Amperex) AX's. 
But to be fair, I need more time.
We are talking of slight nuances, and so all these tests are minisclue.
I look forward to the Siemens which arrive next week.
The Teles  doubt  will ever own, as my tube budget is now bankrupt.
I am sure they are nice, but the german made Siemens will be equal.
Tiny nuances but they are real. 
There is indeed a  resolution variation twix NOS AX7's. 
I've heard about the RCA's reputation, and now i am a  believer, but need more testing to confirm my faith.
Basiclly it will come down to 
RCA tall black plates. 
There are rumors the 1950's RCA are superior to later issues ,,,I am not so sure about that. 
The *Holy Grail* deal to me is snakeoil.
well let me go pay for all my winning bids......