I don't understand the naysayers' demand for proof. Surely, it's not that hard to do listening comparisons of same model components, one "broken in" and the other not. In any case, how could science possibly confirm or disconfirm whether there is an audible difference to a listener? Wouldn't a listener's ability consistently to distinguish the components constitute sufficient "proof"? I have heard a pronounced difference in a number of components--cables, amplifiers, etc. Can I prove this? No. Do I understand any scientific principles or phenomena that would explain this? No. I also can't "prove" that my Acoustic Zen Satori cables sound better than my old AQ Midnight III, or that my Linn Karik cd player sounds much better than my old Adcom GFP-750--but they do. I suspect that the same crowd who used to argue that digital can't make a difference, then cables can't make a difference has moved on to break in can't make a difference. It's a tired move--which isn't to say that some things can't and don't make a difference. Listen for yourselves.