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 Store
Audiobus is the app that makes the rest of your setup better.
How hard would it be to make an open-source synth into an AU plugin for iOS?
I'm talking about the OB-Xd synth based on the Oberheim OB-X. This is a really sweet synth that would be great to have available as an AU on iOS! .
I don't know anything about iOS app development... just asking how hard it would be to port it over since there's already an AU version of it and the source code is freely available.