AudioQuest's current pair of DragonFly models is the third generation of the critically acclaimed DragonFly series, with its big change being higher efficiency allowing for smartphone compatibility.
Plays all music files -MP3s to high-res. Software upgradeable.
You'll need an adapter to make it happen, the black DragonFly modules can take the audio from your iOS (5 and above) or Android (4.1 and above) device and turn it into sweetly detailed music.
If you're only going to listen to efficient cans already designed for portable use, go with the DragonFly Black.