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.
Decent Pitch shifting/Octave doubler AUs (or pitch tracking synths) -- this exist on iOS yet?
There any AU (or combination of tools) around these days that could do what a 'octave doubler' guitar pedal would do (essentially, generate a monophonic tone an octave below a signal)? I don't have the cash to invest in Yonac stuff although I know there's a polyphonic pitch shifter in there. A pitch tracking synth would do the job I'm after really.
It's the only thing that I've not been able to bring into the digital realm yet (have a beat up old stomp box that cost me £25 and sounds maaaasive) and getting it done with software instruments would give me much more flexibility in audio routing.