Right now the current Shuguang KT88 and 12AX7 are on par with the legends of audio.
But, as has been mentioned, in the past, when the military and commercial (telecommunications, radio/tv, computers) electronics industries relied on vacuum tubes as their lifeblood, the importance of building the best tubes possible was light years away from a niche industry that supplies guitarists (mostly) and audiophiles (not many of us).
But, as has been mentioned, in the past, when the military and commercial (telecommunications, radio/tv, computers) electronics industries relied on vacuum tubes as their lifeblood, the importance of building the best tubes possible was light years away from a niche industry that supplies guitarists (mostly) and audiophiles (not many of us).