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.
Dreaming on a complex oscillator synth
I find myself using @brambos Ripplemaker almost exclusively these days. I like the simplicity of it and I like the sound that comes from it without almost no tweak: changes in the wave form, fold and push knobs. It is perfect with a sequencer but unfortunately it doesn't play well with live midi notes.
It kind of reminds me of Madrona Labs Alto. I was daydreaming with a similar synth, with a similar complex oscillator (sine to saw to square) and Ripplemaker's simple one screen interface, push and fold buttons and also its two envelopes.
4, 6 voices polyphony (better 6) with mono/legato option. MPE support.
Nothing else. There are plenty of effects and filters one can add later.
Just thinking out loud.