I have an iOS app where I would like to send out more than two channels of audio output. I'm using The Amazing Audio Engine.
I've done this with the Apogee Duet by simply setting the mChannelsPerFrame of the ASBD that I initialize the AEAudioController with. However, this does not work on the Presonus 1818VSL interface. I only get audio output in channels 1 and 2, just silence in any of the channels 3 and higher. I have observed other apps working fine with this interface, so apparently it's not a hardware issue.
Is it possible that the interface is expecting audio in different "buses", a.k.a. output elements?
Buses are not the correct answer. Simply initializing the audio controller with an ASBD where mChannelsPerFrame is set higher than 2 is enough.
My confusion stemmed from a crash in TAAE that was obscuring other bugs. It's been fixed now - https://github.com/TheAmazingAudioEngine/TheAmazingAudioEngine/issues/245