I felt that I heard improvement over the first three weeks, which is to say: over 30-40 hours of listening to fairly diverse and often energetic music.
This is my first set of high end headphones.
The sound is great out of the box, just curious if it gets better. I guess I'll have to wait.
The sound is so realistic, these have such high resolution, I'm noticing alot of "faults" with many of my favorite tracks.