Someone just asked me how to do this. I have no trouble because I use "Logic". But this guy has just the software Apple ships with a new Mac. It seems GarageBand has no way to send MIDI to digital piano you might have connected. It does fine for recording but this guy needs to render a MIDI file to audio in the MIDI connected keyboard. Seems odd Apple would have left this feature out. Is there a way to do this without buying Logic Express? Is there any other low cost or free software he could get?