component break in

I agree with Buconero. You can run pink noise through the speakers for 24 hours, but if it takes more time than that, let the dealer do the work. Tell them you need a little break in time before spending your money. There's no guarantee you'll like the sound even after (getting used to it) break in time. By then, it may be too late to return them.

Buconero117 and Polk432 make an excellent point. For stuff needing a long break in, tell the dealer to do it, then you will be able to make a reasonable judgement in a reasonable time.
IF the dealer really believes in the long break in.. they should be willing to do it. If it is just Bs to get you to keep stuff you do not like.. then you know to pass on it.
Put the onus on the dealer.

it depends upon the manufacturer of the product.

i have been told by two manufacturers that there is no need to break-in a component.

if it has tubes, one hour is sufficient.

there is no definitive answer.

there is an easy way to determine when a component has broken in.

listen to your stereo system. if you hear changes, break-in has not yet completed. after a while, you will notice that your stereo system sounds pretty much the same from day to day. of course there are normal variations from day to day, as a consequence of several factors.

before placing the "new" component into your stereo system, listen to your stereo system for several days in a row, to appreciate the subtle variation in sound, if there is any. then introduce the new component.

my experience is that one week of a signal is the minimum break-in period, but sometimes it is longer than that.

i was reviewing the cable and i thought it broken in. one day i was listening and i realized that i was wrong. the cable was continuing to break in and its sound changed after i had submitted the review. i believe the cable had 300 hours of a signal passing through it before i evaluated the cable.