It is interesting to know that using two Output Type audio units is actually tolerated!
Did you look at the AGC property of kAudioUnitSubType_VoiceProcessingIO ? You might want to turn it off (on by default). Can't think of how it'll handle two outputs
Did you manage to work with multiple audiounits ?
I wonder if I can have voiceprocessing audiounit for Microphone and remoteIO audiounit for Speaker
@zvba : You can't have a voiceprocessing audiounit with remoteIO. One major reason is that VPIO requires specific AVAudioSession Category/Modes which are not the ones you can use with remoteIO. I had the chance to talk with CoreAudio developpers on this at WWDC.
This won't get any better with the new AVAudioEngine support for VPIO (which I think uses the good old APIs under the hood).
A nice solution would be to have enough controls over VPIO to get what we want. All this, for an undetermined future... .