To add a little more color to Perseus' response...
Fresh out of the box, a pair of headphones may not sound as good as a well used pair, as the designers have intended. Often, people want their headphones to sound the way that they are intended as soon as possible. Most people don’t want to wait for weeks or months of regular use, so the choice is to expedite burn in by getting the process over with in the first week of ownership. Others choose to listen to their headphones as they change over the burn in period.
All the best,
PAN
