Tried a little experiment. Took a weak testing RCA 12AX7A (32/36 min 32) and compared it to several new production tubes in V1 of a silverface Vibro Champ. Even at close to the end of it's life, the RCA seemed to have more clarity than a JJ, GT (Russia), or Ruby (China) that was fresh out of the box. Kind of goes against what I was expecting from a weak tube. Or is a weak preamp tube less noticeable than a weak output tube?