Why do new cables needs to be "broken" ???

This topic reminds me about the story they told us in college pyschology 101 about how they put prism glasses on some test subjects that turned everything upside down. After some time, these people's brains flipped the image back again so they could see thing normally through these glasses (or so the story went). Their point was that what people see is what the brain does with the raw data it gets; all the sensory input is interpreted or mediated. Through an act of pure will, we can train ourselves to use the raw data differently.

30 years later, I'm not sure I buy this 100%, or even 50%. I think there are plenty of hardwired responses that you can't override easily. I think the answer lies somewhere in between. It would be really easy to dismiss break-in as just a way the salespeople use to make you keep something so long it's too late to return it. But dang if I haven't heard it myself.

First off let me say, I have no idea why cables need break-in nor I have I ever heard a satisfactory explanation for the phenomenon. Many here dismiss the phenomenon as non-existant because it can't be explained. There are many phenomenon whose existance is generally accepted without currently viable explanations. Really nothing new, happens all the time. Can't argue that a dose of skepticism isn't healthy. But to argue that cable break-in doesn't exist because its existance can't be scientifically proven goes against many audiophiles direct observations, including mine. Observation after all is the beginning of empiricism.
Quoting from the Stealth netsite:
"According to our point of view on the break-in process in cables, it mostly deals with the 'ground potential differences' in the componants used."
I quoted this because, perhaps the componants being connected are as important the connections in this process. I really don't know the reasons behind cable break-in and I don't think the cable manufacturers know either. What I do know is, depending on the cable, it can make a huge difference in the "sound" of a cable.

Break-in by & large is an urban legend, even for the golden earred in the boonies.

Well put Rja!!!!