Kt88 or 6550 tube for McIntosh MC275

I just posted a series of answers on this very topic last night.
6550=kt88

<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>.

One was designed in the US one was designed in the EU.

They physically look different, as does the KT 90 you reference also.

They are not the same, nor do they sound the same. ALL 3 differ in design, and vary from manufacture to boot.

6550 does not = KT88 and certainly not a KT90 valve, different all together again.

I read your findings, I had to wash my face with cool water and take a TUMS! Pure bla bla bla...

Please! You started a tube flipping business right... and paid 1500.00 for a pair of valves.

TUBE FLIPPING.  I admire you're stones... Mercy

VA, It's stands for Valves Anonymous. Might help. GA, Gamblers Any, AA, NA...

Regards

SED

all Svet issues, SED, Winged C, NOS, New Prod, are all =. Just go with new production. 
Especially if you need close matching. 

KT90 is quite dif,, has some points over the 6550/88, but for open-ness soundstage, go 6550/88. 
 Here you go makea  compare, 
'all 88/6550 ever made, the specs are so close = makes no difference, 
like twin brothers.
Not 1 audiophile in the world could detect a  blind test A/B twix 6550 vs KT88.
Impossible, as they voice near identical. 
Sure there may bea  mini-scule dif twix every lab's 6550/KY88, even there it will be tiny. 
So to sum up
6550 vs KT88, mini-scule dif
Brand X vs Brand Y KT88 miniscule dif.
Thats said, I am in agreement with another audiophiles opinions of the GL's, He did not like their voice, and neither did I./ 
These Svet voice beautiful and are made like tanks = Gold Winner in my book

https://frank.pocnet.net/sheets/049/6/6550.pdf

https://frank.pocnet.net/sheets/164/k/KT88spec.pdf

There are no new SED, Winged =C=, Svetlana tubes in production. I really liked them, but- the St Petersburg plant burned down, years ago and SED closed the doors.     Some info from a reputable dealer: https://www.thetubestore.com/winged-c-sed-6550c           and: https://www.thetubestore.com/tube-brands/sed-winged-c (read the bottom of that last page)      Try contacting known to be honest tube mongers, like the above, Brent Jessee Recording, TC Tubes or Upscale Audio, for knowledgeable advice.

painful ignorance on display in this thread, coupled with bravado and confidence

oldhyvme - don't waste your breath

ugh