I actually use the Shuguang Black Treasure KT88-Z in my Granite 864-SR. I also have a pair of the Sylvania 6SN7GTA Chrome dome 3 hole black plates and 2 pair of Jan CHS (sylvania) 6SN7GT-VT231..
If i try to use the SylavniaGTA in V1 and Sylvania GT in V2 or any combination of these in V1 or V2 .. I lack BASS.
I had originally ask for and tried the Ken Rad 6SN7 with the Sylvanias V1,V2... kiler bass , but Ken Rads were Microphonic. I then tried some Tung Sol Round black plates . They were also microphonic. I asked Andy to send me another pair of Sylvanias that have good bass... to use with the other Sylvanias , his reply was that none of the Sylvanias can do Bass as well as the Ken Rad or the Tung Sol, (cause once i heard the bass with the Ken Rads and or Tung Sols .. i had to have it) Andy actually said that the only 6SN7 tubes that can do Bass like I heard and wanted was the Ken Rad or the Tung Sol
So if using two Sylvania 6SN7, one in V1 and the other in V2, and it did not matter which Sylvanias (i tried. I tried all but the Metal Base ones) the Bass was lacking .
As a matter of fact most of the combinations of 6SN7s in V1 and V2 in those amps, lacked Bass IMO. ...unless i had a Ken Rad or Tung sol in V1
That was my experience with 6SN7 tubes.
Therefore i know use a 6F8G in V1 with the 6SN7 adapter.
https://www.ebay.com/itm/Tube-adapter-6F8G-to-6SN7-1-pair-/153299100833?item=153299100833&ViewItem=&nma=true&si=apYGBdYiWyN493VkmTacst7L9wQ%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557 .