"Burn in" Are you serious?

I had the oppertunity to compare a brand new pre amp with the stores demo pre amp in my home. Although both were the same brand and make preamp there was a huge difference. The one that was broken in was more open and a lot smoother.

If it goes to reason that if someone can hear a diffrence because they want to couldnt the reverse be said that some people dont here the difference because they dont want to. Just because there is a science to pchycoacoustics doesnt mean it applies in every instance their is a disagreement. Just because I cant explain it in a way that convinces you doesnt mean it doesnt exist. And lastly just because someone cant hear the difference doesnt mean someone else cant. I use to run a small metal fabrication plant. The properties of metal changes during anneling at certain tempatures and after passing current through it. I think someone above had it right. Go out to Radio Shack and buy two pairs of cables and compare them after one set is burned in.