Do cables really need "breaking in"?

I've done direct fresh VS "cooked" speaker cable A/B's twice. First time with 4, identical 5 foot lengths of Kimber 4TC cut from the same spool and terminated in the same way (spades with Wonder solder). I was going to Bi-amp my Acoustat 1100 and needed the 4 identical lengths. First I listened to them fresh as pairs in a single wire configuration to make sure they were working ok. The two pairs sounded identical. I left the last pair hooked up to the 1100's and hooked the first pair up to my Duo-Tech enhancer in the basement. And I promptly forgot about the first pair. I then went on vacation for over a week. Upon returning, I fired up the system and 1100's and everything sounded as before. I then remembered the other pair of 4TC cooking (about 10 days by now) in the basement, brought it back up and swapped it out for the "fresh" 4TC pair. I sat down and pressed play.....GOOD GRIEF. The difference was immediate and not subtle. More open, more relaxed, more liquid, more quick..the usual suspects. I went back and forth several times between the cooked and fresh pairs of 4TC and it repeated each time. Things with the cooked 4TC got even better after about a day of "rest". I repeated the same basic experiment (this time with Apogee Slant 8's) when I upgraded to Audioquest Sterling II. Results were very similar but not to the degree as with the Kimber (the single 25 foot run of Sterling already had some time on it).

I'm not sure why there was a difference, but a difference there definately was and it was quite beneficial. I have a similar story with interconnect wire.

I really don't know the answer to this, but if cables can sound better after time, why doesn't your TV look better after you've been watching it all day or why doesn't the radio in your car sound better after listening to it for hours? I, personally, have never noticed any changes in any of these. There may be very subtle changes, but don't think there would be any major change.

Sean: First of all, I don't like participating in discussions in which someone tells me to "shut up." As for your "flat earth" reference, I don't think anyone here wants a discussion on scientific method, so I will only state that all of your experiences with a particular product do nothing to challenge the suspicions of some of us that perceived changes in cable sound over time may well be a psychological rather than a physical phenomenon.

SMW30: not all situations offer the resolution necessary to hear the "breaking in" of cables or electronics. The car is one good example, where the ambient noise is so great, you would never hear those changes. As for the TV: Most of it is on all the time, so its not "all day" thats critical but whether its brand new. It definitely looks better after a few weeks of watching compared to brand new. This was very evident with my projection tv. My DVD/CD transport got much cleaner and smoother after about 3 weeks of use.

Maybe some surface oxidation of the conductor occurs (which will make the sound slightly less bright. Perhaps some charging of the dielectric insulation occurs. I would not discount the possibility that the (measurable) characteristics of the cable change, but I'd like a proponent of the burn-in theory to show me their measured results.

However I think it is more likely a psychological effect : the brain rapidly adapts to new tonal balances, and comes to like them. I have a hifi in England at my parents' house and one in the US both of similar quality. I have noticed that on my vacations in England in the first few days my UK system sounds worse than my US system. Then when I return home the first few days after I get back my US system sounds worse. Over the long term I am very happy with the sound of both systems ... they're just tonally different.