Why do amps, pre-amps, cd players, speakers, cartridges, and everything else in your system need to be broken-in? The reasons are complex, but the simple answer is that the wire has a crystaline structure that presents many options to the electrons as they negotiate the path one copper molecule to the next. For the first few hours of use the electrons will be seeking the path of least resistance between every molecule. Once that path is discovered, the current flow is much smoother even though the resistance doesn't change. If you take your cables and disconnect them, roll them up and store them, the path will be lost and you'll have to break them in again. Yes, the same holds true for interconnects.
Why do cables need break-in?
I just had the experience of having newly introduced speaker cables (AudioQuest AQ-8 bi-wire) break in. When I put them in a few days ago they sounded thin, bright and lacking in bass. Now, after 4 days and 40 - 50 hours, they sound far better: relatively neutral frequency spectrum with much more bass weight. I'm delighted, of course, but I'd like to know why this happens. Will I experience the same scenario when I change interconnects?