That is a big question that alot of guys ask, personally I dont do a "break in time" with my new stuff..I have heard of guys letting them run free air at a very low wattage for a few hours...If they are good subs though u can be the sh!t out of them straight out of the box..They will loosen up overtime... what type of subs are they..
You really don't need to do break in. The suspension will losen up on it's own naturally, just play it like normal. It can take days, weeks, or months to fully break in a sub, but that doesn't mean you need to treat it differently.
i just play them straight out of the box to tempting lol. I havent had a problem yet. The sub does get louder as time goes on i am definetly noticing this with my mag it gets louder and louder everyday.