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.
Rating and reviewing what you praise here in the actual store(?).
Not many seem to do just that. Take (Audiokits) Audiotune as an example - it has one rating. All devs say the same thing: "please rate and even better - write a review!" So, if you do appreciate an app or have something in general to say about it, don't limit that to here alone but go to the store as well. I will try to get better at it myself.