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.
I know I’m a little late to the party but I just want to give ThumbJam some love and recommend it to anyone who hasn’t discovered it. Not only is it a fantastic app by itself and very deep (if you want it to be) but it’s great sounding sampled instruments (of which there are many) can be routed to other apps - for example to Fugue Machine through Aum.