I have a Cowon A2, and would REALLY recommend different IEMs with a Cowon player, particularly the Future Sonics Atrio. I've always found Etymotics to be uncomfortably bright, and the analytical sound of Cowon players would not be the best synergy. The Atrio smooths the highs of the Cowon, and the Cowon sound tightens up the Atrio's bass response. A superb pairing. I am, of course, talking about using the player with a flat EQ.
Good stuff! I'm envious of the A3. Especially since the headphone jack on my A2 is wonky at the moment. Heh.