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 have….let me look ( press the button ) 5,188 hours, blissful hours on my Ref 5se. In this preamp, this circuit this tube matters. As do tracking the hours on it. ARC recommissioned 2k hours on that tube. I have about that on a NOS New Jersey Tung Sol from the 60’s. It transformed the bass and mid bass in my system even vs a new direct from ARC tube. Andy at Vintage Tube Services. i trust him. 
There have been man anecdotal posts over the years regarding tube rolling in ARC Preamp’s, and the 6550 in their power supply definitely changes the sound....and I can “parrot“....ah I mean 
confirm, (😊) , this in my observation as well in my REF 6 SE......
Cheers....

Audible differences can cleanly  be heard with any old Jimmy Buffet song, fellow Parrotheads…
that 6550 is not in the signal path, but I bet you will still hear a small difference. 

I would be inclined to try a PSVANE KT88 gray glass tube...