Just keep in mind that the majority of headphones will take several hours breaking-in. The mobile membrane should accomodate and loose it's stiffness so that the sound becomes enjoyable. These is even more significant when talking about small headphones. Some people buy them, plug them pristine, and expect to ear miracles. Just keep them connected at medium volume in some music player for two days or so and ear the difference.
My Pionner SE-CL21 did benefit from the breaking -in. They where rather dull when I bought them but now they play nicely!