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 StoreAudiobus is the app that makes the rest of your setup better.
Comments
The mixer shows decibels, the scale is at the side. Signals over 0db appear as red in the level indicators
Keep in mind you're not going to get distortion inside Loopy Pro itself. Distortion can come in if the signal passes into FX apps that do introduce distortion (intentionally or not), on the master out if the DAC clips, or at the input of your interface.
This means that the real place you need to measure DB levels varies. Monitoring the level of an a channel output doesn't tell you if you're overdriving an FX on a send for instance. Nor does monitoring the output level of an FX if it's being over driven at the output.
The key is to think of where the distortion can be introduced. Individual internal channel outputs isn't one of them. That's a holdover concept from analog and pre 32-bit digital processing days.