When I try to play two audio sources at once, only one plays and I get the following warning: iPhone supports only single audio source with compressed audio. 1) Does this mean that if the audio is not compressed I can play multiple audio sources at once? 2) Or am I limited to only one audio source total? 3) I noticed that Zombieville can play a) music, b) gun shot and c) hit sounds all at the same time. Is there a trick to this?