[Kickstand]

As the title says I am looking to upgrade from my Beyerdynamic DT770's.  They are the 2005 consumer edition cans @250 ohms. Cabled with starquad.   My current contenders are the Sennheiser HD650's and the Grado RS-2.  My price range is up to about $550.
 
Music I normally listen to is rock and rap with some house/techno/dubstep thrown in depending on the night. I am not a total basshead but I do like my bass to be controlled with some oompf behind it.  Comfort for long period of time is a definite priority as well as a large sound stage.  Looking for something open this time around compared to the sealed DT770's.  Sound leaking isnt an issue. 
 
Source is my imac but I am currently looking at USB DACs due to a hissing issue I am getting.  If I need to buy an amp as well I have no problem with that. I know my Beyers would benefit from one but it isnt something I have gotten around to purchasing yet.
 
 
Also if anyone is interested in they Beyers in the CONUS I would be willing to cut someone an awesome deal on them 

 

[violinvirtuoso]

The RS-2s probably aren't what you are looking for. The DT770s are a bit bass-heavy. You should look into to some higher-end Ultrasone headphones.