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.
Steel Guitar Pro from Yonac - not really usable with anything else
Ok if playing stand-alone using the screen as then interface.
Issues are the MIDI learn does not work, well for basic functions like volume control and sustain.
You cannot even set these manually (even though there is capability to do so) it simply does not "see" anything else other than note data.
Developer must have created it thinking it was the ONLY instrument being played and hence played directly from the iPad screen....certainly is not set well for controller keyboards.
Sent messages to the developer with nothing but silence! It's a shame as some of the sounds are really good!
Oh and, annoyingly, it creates a double (audible) pop/click when it loads even with volume set to off. Quite loud when running through a PA!!