They worked ok for me. I tried them on different tubes and got different results. Overall, I liked what they do, and am using them in my system. But I didnt like using them everywhere. This deserves a retest, since I'm at a loss to say WHY the sound would be worse. One explanation is that I have an unsophisticated ear and like noise. I say buy a pair and play with them. There is no price break of any kind for quantity purchases so why buy too much? At any rate, they're returnable.
The Cheapskate
The Cheapskate