Break in is all marketing BS promoted by DD and the inbred cousin AQ. Common sense is the only thing you have to worry about.

what do they gain by telling people to be gentle on their subs for a few weeks?

Not sure they gain anything! Local DD dealer here in town say's to break them in, but yet they say turn it up right away DD can handle anything.

I have an AQ SDC2.5 15" it's nothing special by any means, ok output but the sq.....meh!

see i just got a freshly reconed hdc3 15 and i think it sounds great, and gets hella loud. the reason i was wondering about break in is bc aq says to break in the sub and i have been trying to figure out why they recommend that when everybody else says its not necessary. the only reason i could think of is because the recommend a high tuning and we all know that if u play too far below tuning you could tear ur spiders...but when they recommend upwards of 36hz tuning how much lower can you play them without messing something up?

I guess you could say to take it easy at first to make sure everything is good to go with glue joints and alignment. I would say after awhile increase the volume and listen for stress in the woofer. Use your ssf to adjust as needed. Should only take an hour or so not weeks like they DD/AQ say.

ok that makes more sense...thanx for clearing that up. i mean i know what to watch for and smell for, but others may not.

see i just got a freshly reconed hdc3 15 and i think it sounds great, and gets hella loud. the reason i was wondering about break in is bc aq says to break in the sub and i have been trying to figure out why they recommend that when everybody else says its not necessary.

They cater to the least common denominator...and they do this in more ways than just recommending that you break in their subs. IMO there are tons of better options for the same price. Not knocking what you have in particular if you bought it used for a good price, but I'd still have chosen something better for your needs. Rarely does one of their drivers fit those for nearly anyone.