Wow! some really strong opinions here on the whole tube thing.....
I, for one, do hear a difference among various tubes. And you know?, it probably IS less than 5%! 8)
But I can hear it, none the less.....
I feel there is validity to both sides of this argument. Tone originates in the fingers....but certain amps, effects, and yes, even tubes, can enhance or detract from this.
I do think it is generally foolish to spend excess amounts of cash on all different types and brands of new, old used or NOS tubes, unless you have the means to afford it and enjoy doing it.
Most of us are better off to find a brand we like and then replace only when needed. I was fortunate enough to come across some old (and FREE) tube HI FI gear that came with a variety of the older American and European tubes.
And I'm sorry, to each his own, but I can tell a difference. 8)
However, I won't deny it could be considered subtle.
But after putting Telefunken and Amperex ax7's in v1 and v2 of my Ace and Triaxis, Mesa tubes will never go in those sockets again! Except as an emergency spare, maybe.....
I can accept that this just might be me and my opinion.
I admit it is unlikely I would have spent $50, 60 or more on some NOS Telefunkens when the quality of new production tubes is increasing daily......
But now that I have them, I'm using 'em and liking 'em a lot....
Good luck to you all