It's probably different for subwoofers but about a month ago I bought a set of kind of high end components. The guy that sold them to me said they take about 50 hours of play time to break in. I thought that was a little excessive but it has actually taken about that long. They didn't really start moving until just recently and I listen to my stereo 2-3 hours a day on most days.
Well if you want to break them in... which I don't know if there really is such a thing. Just keep the amp at half for a week, and the volum no more then half way. Then after that week adjust the amp to what the subs can handle and that's that.
I've never even heard of breaking in speakers.....although I probably ran through a similar process just by coincidence. I bought my sub a few weeks ago, and at first I wasn't used to hearing all those low tones, so I kept pretty low gains. After a couple days, I noticed that the low end was kinda weak, and that I was hearing more of my mids and highs than my bass. So, I looked at my amp...a long story made short, my sub gain was turned about half-way up, my bass boost was still off, and the rest of my gains came down, as of yesterday. As of today, my sub gain is topped out, and my bass boost is at about 10dB. Suddenly, I enjoy the way my seats shake like mad, and my hair stands on end with about 2/3 volume from my deck. So, there you have it.
Some speaker or subs do sound better after a little bit of use, maybe because everything loosens up but I don't thing a "break in" period is called for.
Some companies actually send something in the box saying that you need to break in the subs...
the tempest need a break in. got it on thursday and didn't really sound loud till about sunday. saturday was the first day i turned it past half, and u could really smell the glue burning. i loved everysecond of it.
treat a sub like a car engine, would u rev up an engine to red line if it has 50 miles on it? nope