I'm sure its been mentioned a few times in this thread, but please remember that your headphones will only be as good as your source. If you don't update your source before updating your headphones, you're really doing yourself a disservice.
If you're like me, and mostly listen to digital sources (MP3, FLAC, ALAC, etc), that means DAC. Which is why buying even a small DAC/AMP combo will go a long way to making your existing, let alone new, headphones sound better. This is assuming plugging it into a computer, or a device that allows either line-out or USB audio.