Email any manufacturer asking "Should I break in my new subwoofer and if so, for how long?" and you will most likely get a response like this "There are many mechanical parts needing a break-in for a minimum of 20 hours and up to as many as 150 hours". Truckloads of studies have been done on this subject (Tom Nousaine, David Clark, Richard Pierce and more) and their conclusions contradict what the manufacturers claim. Although the suspension does in fact soften up, the important parameters change in such a way that the box size and frequency response is not effected (Fs and Vas for all the other audio nerds out there). Double blind subjective tests have confirmed that there is no audible difference in a "broken in" speaker and "fresh out of the box" speaker.
So why do almost all manufacturers recommend a break in time? Don't they have access to the same studies that everyone else does? Cynically one might make a case that they want the customer to keep the subwoofer for an extended period of time to get used to the sound. Humans have an amazing tendency to adjust to any type of sound and manufacturers surely know this. A more optimistic approach is that perhaps the manufacturers do it so that their product gets a fair assessment by the consumer before they hastily denounce it. Another theory is that the manufacturers are simply conforming to what all the other companies are doing. The reasons really aren't important. The important thing is that now you have the knowledge to know that however your new sub sounds on day one is how it is going to sound everyday.
