Great detective work by Peter Kirn of Create Digital Music.
2. USB MIDI support for class-compliant devices, using the iPad Camera Connection Kit’s USB adapter
And on power requirements:
There’s one significant caveat to USB connections: the Camera Connection doesn’t carry a lot of current, so devices may require an external power source.
I tested this with my iPad, and it happily powers my Axiom 49 keyboard. I’m sure it will power most other USB controller keyboards.
Imagine setting up your phone as a high quality sampler in a musical pit or on a stage.
This is the single biggest music on the iPad story about to happen.