There where 3 major errors in the previous code:
1) The kAudioDevicePropertyPreferredChannelLayout selector returns a single
layout not an array.
2) The check for AudioChannelLayout allocation size was wrong (didn't account
for variable sized struct).
3) Didn't query the kAudioDevicePropertyPreferredChannelsForStereo selector
since I didn't know about it's existence.
All of these are fixed.
Might help with #1367
Stefano Pigozzi
562e42f826