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?
pendragn
True, Dekay true, LOL, treat 'em like you would a big bad bronco and ride them real hard ( Put a Kinky Freedman CD on replay for 10 days or so ) apologies Pendragn, still off topic..
My thanks to 2001impala, Sugarbrie, and Audiopath for their explanations and for taking time out to provide them. As for you other guys, try this: My wife and I have a wonderful marriage. It's probably because we go out twice a week. She goes out Tuesday, I go out Friday. (<--courtesy of Henny Youngman):}
Could someone please produce some sources for this? Like, not from people selling cables.