There is one audio output connector on the Axon HD, the additional Mini-Jacks are Mic IN, and Line IN, these connector are not used at this time. The Axon HD software makes use of the 1.5mm Mini-Jack connectors - Left / Right (colored green) only.
Audio information is logically contained on layers, meaning that multiple audio streams can be output at once. Cross-fading between audio layers is fundamentally the same as cross fading between video layers. Be aware, if using video content containing audio while using a collage, it is best to choose one file to output audio, not multiple sources of audio.
Audio is disabled internally any time the play speed parameter is adjusted.