Actually the component break-in side of the equation depends a lot on what kind of capacitors are under the hood of any electronic device. I've seen electron microscope images of how the electrons actually make a pathway through the dialectric, much like wearing down a foot path on the grass.
The big issue is usually with teflon caps, and they usually take 3-500 hours to sound their best. The dialectric of a teflon cap looks different at new, 100, 200 and 500 hours.
Every piece of gear we've ever reviewed that is full of teflon caps (modwright, CJ, BAT, ARC, Aesthetix and a few others) usually sound pretty dreadful right out of the box. Just for laughs, Dan Wright at Modwright let me have a pair of preamps so we could prove this to the uninitiated.
We ran one preamp for 500 hours and left the other in a box. After almost a month of play time, we A-B'd the two units that were identical and the difference was almost shocking.
Most of the run of the mill stuff is usually about 20 - 50 hours. Sometimes a mfr will put 20-50 hours on a component before shipping it, so this is less apparent.
My experience with speakers has been 20-100 hours for the most part, but as many of you have mentioned with Summits, that it does take a bit longer. It really depends on how much time you can play them continuously too.
One of the major reasons that a new pair of speakers doesn't sound quite like what you heard at the dealer (or the pair they let you take home) is that the new ones you buy aren't fully broken in.