In this video, iPadProAudio explore several useful iPad audio interfaces, including the Alesis iODock, Apogee JAM, and Apogee One. Note that this video was created before the Lightning dock connector, so an adaptor or updated device may be necessary on the latest iPads.
Source:
http://audio.tutsplus.com/articles/lectures/on-youtube-ipad-professional-audio-interfaces/