I'm into my M50. It's probably the first fully closed headphone I've ever liked, and that includes the big guns (well, not the R10 or L3000

) The soundstage is restricted compared to an open can, but other than that is sounds really natural. My only complaint is that the sub bass can be a bit much, which is only a problem for me with bass drum, which is more pronounced then with any other headphone I have. And the mids are just a bit back in the mix. But it doesn't really bother me when I'm listening to them- I'm not distracted by it. I just think the phones would be that much better if the mids were farther forward. But fantastic phones nonetheless. They manage to have a lot of treble detail and plenty of treble energy for them to sound natural (not dark or recessed) without a hint of harshness, which I am very sensitive to.