I am not a subscriber to the concept of break-in of the headphones themselves. I think they sound exactly the same on hour 1 as they do on hour 10,000. But I am a subscriber to your brain adjusting to the sound of different pieces of equipment over time. So if you give them some time, your brain will adjust and I suspect they'll sound better to you after a few days.
That said, they are a bit muddy sounding and less than fully detailed. Turning up the volume, as many have observed, is a bit of a way to overcome the challenges that these headphones present from a frequency response perspective.
More detail is apparent at louder volumes, but at just that level where it can be fatiguing. I find this to be less so when I dial back the bass, others might like more treble, etc. But if I'm being frank, the need to play them louder is more of a sign of a design flaw than anything else.