Should add that I'm looking for usb powered. As I wont always have an outlet around. Thanks though! 

I researched as much as I could but I wasn't finding much on the subject. I am looking for an amp or preferably an amp/dac combo to power 250 Ohm Beyerdynaics. I currently have a Fiio E7 and I feel like I'm not getting as much as I could. It will only be used with my laptop though usb so battery...