I received my T8 on Tuesday and the tubes in it are labeled Sovtec. I found the same information as "thechairguy" about the single Voskhod factory. I don't know if that factory is part of the parent company New Sensor Corp. that makes Sovtek, Svetlana, Electro-Harmonix, Tung Sol and........tubes.
The sound: I sold my bigger and better Carver amp, until the 550 gets here I'm listening through a lesser Carver amp (that must mask alot of the T8) but it is sounding better than it ever has. Briefly, (much more after the 550 arrives),the sound is much more dynamic, much quicker, more open, bigger but more focused, alot more resolution, much more linear, more depth, richer and I guess in one word, more musical. Each night it sounds better.
WEEZ, earlier you asked about the gain. With the 3i the volume knob was usually at "3 o clock", with the T8 it's around 10:30.

More later
Marty
P.S. Apparently, according to "thechairguy's" Wikipedia quote it's not part of New Sensor Corp.