[Mat5t]

I got these last Saturday, 12.28.13 and have some issues. I have had them on almost the entire weekend and so far, this is what I have found. I am a Mix/Mastering Engineer and bought these to use as a reference. I use an RME Fireface 400 as my interface.  I use Foobar2000 to listen to my music library, which is all lossless audio. Now here is the strange thing. When I listen to Jazz or Classical music, the headphones seem ok but not amazing. But when I listen to rock songs they sound very muffled. I mostly do rock songs when I am mixing/mastering. Is this something that is going to improve over more time with the headphones, or is this what it is... I know that everyone loves these headphones, but right now I am not seeing why.  How long do you think I should I give the headphones? Will they even get better over more time, or is it how it is going to be? If not, Is there a different headphone that you recommend that has more air?