Best modern 6550 tube for ARC per-amp


There are a lot of modern 6550 tube in the market such as Reissue Tung-Sol 6550,  GE-6550A (Green letter), Svetlana 6550, Russia Gold Lion 6550/KT88........etc.  What is the best modern 6550 tube for ARC per-amp in your opinion?  (PS: GE 6550A is not newly made but still a lot in the market).

I used to own a NOS black plate 3 holes Tung-Sol 6550 but which has leak and now I’m using the stock Svetlana 6550. I want to buy a nice sound 6550 for my ARC Ref 6 and my stock Svetlana 6550 will be used as spare. Will not consider NOS black -plate Tung-Sol again because of pricy and not sure the condition.


mmbl622
I run various KT88 and 6550's in my ARC Anniversary Reference preamp along with Herbies tube dampers in all spots and can hear a difference between tube brands/dampers,  I also roll 6n6p tubes as a drop in sub for the 6h30p's for a very nice (and cost effective) upgrade...
Anybody who have experience to compare the sound quality of these tubes:

Re-issue Tung-Sol 6550 vs GE-6550A 
Svetlana 6550 vs GE-6550A

Someone offer me a 2nd hand green words version GE 6550A which is slightly use (asking the seller how many hours is use) at US$78.   Not sure how's the sound quality.

Another concern is not sure how's the condition of this tube because this is a used tube. Although the seller said it is only slightly use , I don't know how many hours it has been used. And I don't have any tester to test it. 


So, now one of your proposed strategies is to place a tube of questionable history, possibly fake, and with untold/undetermined hours of use in your $15,000 preamp? Right, makes perfect sense.
@tubegb

So, now one of your proposed strategies is to place a tube of questionable history, possibly fake, and with untold/undetermined hours of use in your $15,000 preamp?


lol...

well i guess we have all scratched the scab off of a healing booboo, make a bloody mess ... sometimes in spite of what is good for us... path to nirvana is often over some rough terrain in parts
Indeed, far from perfect. I could recount/regale endless stories of questionable moves/decisions made over the 40 years in this "hobby"...