Not to derail this thread further but...

The essential link in the iPad/MicroArranger setup above is the Alesis IODock II which happens to fit perfectly with the MA's music stand. I tried a couple of clunky IOS audio/MIDI interfaces and the Alesis unit worked best. The fact that the music stand holds the dock nicely was luck. The Alesis IO Dock II provides low-latency noise-free interfacing, good controls, and it charges the iPad when in use.