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.
A truly fascinating view of the history (and future) of music
I know Rick Beato can be bit of a issue for some people, but his guest Ted Gioia is a truly fascinating guy with tons of ideas about how musicians can discover new ways (in the near future) to monetize their music.
He also covers a great deal of music history and would probably make an awesome TED Talks guest.