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.
Digital D1 AU version bugs
Still major bugs in the AU version of D1 synth: If you save a different Mod Wheel setting with a patch in stand-alone (e.g.Tremelo), when the same patch is opened in the AU version within AUM, the Mod Wheel always defaults to Layer. Saving an AUM preset after changing back again doesn't help - still loads the default mod wheel Layer setting.
However, changing the setting within the AU version and attempting to save the D1 preset within the app, will cause D1 to crash. Every time.