We are trying to get multi-channel audio (5.1 surround sound) to playback on iOS.
We have developed an app that is mapping 5.1 .wav files perfectly, but when the same files are encoded to ALAC, AAC or AC3, all channels are mapped to Front Left & Front Right only.
Hardware is iPad Pro → Lightning to USB 3 Camera Adapter → miniDSP U-DAC8
Lightning to USB 3 Camera Adapter:
More details and test files here:
We can pay a little money to anyone that can help.