Igor Vasiliev's Master FX got its first update adding IAA!
What's new in MasterFX v1.1:
- Inter-App Audio supported.
- Waveform view of player files.
- Loop mode for playback.
- Improved compressor module.
- Several new presets.
- New color schemes of visual interface.
- Built-in description updated.
- Some bugs fixed.
There is also this excellent sounding new demo showing off the app with an acoustic guitar.