Yess...
At first - in th elate 80ties i thought, that Aspen invented that...
Afterwards i found Ads for genuine "factory matched pairs" of old Mullards...
So the "art of matching" might have been something from long ago...
Grüße
Jochen
Good point. But as far as guitar amps go, I think Aspen really got the ball rolling.
Hard to believe that we used to take out tubes to the local drug or department store, test them there, and buy what we needed. I remember buying RCA 6L6s for $6 each. Matching? Biasing? What?