Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
Use GarageBand as MIDI Controller with Audiobus
In Audiobus 1, this doesn't seem to be possible, but maybe it is in 2. I'd like to set GarageBand not as my input device, but as my output device so that I can run its MIDI into Music Studio. The idea being that I could then use the built in "automagic" MIDI synths to play the MIDI instruments in Music Studio.
Comments
If I understand what you're asking it's not possible but it has nothing to do with AB. Apple won't allow GB to be used this way.