Haven't had much time to do comparisons yet. But initial impression is that both D2000 (slight Dynamat mod) and the X1 are better headphones soundwise. Bigger soundstage on both being the most noticeable difference so far. But the Momentum is really nice and I like it a lot, bought it mainly for travel and was not expecting full-size open sound anyway. I'll try to post more impressions later.
Edited by HiFiRobot - 4/30/13 at 10:25am