If you are comparing these to the m50s, just look at the reviews on amazon. At least 10 reviewers said they were much better than the m50s and several others called them better than the dt880! I got mine at $140, which is a killer deal. At their current price of $236, they are still a good deal, but I might wait for the price to fall.
You can also read my review here: http://www.head-fi.org/products/audio-technica-ath-a900x-art-monitor-headphones-japan-import
Edited by chili dude96 - 8/1/13 at 10:25pm