When I play back an mkv video file on my Macbook Pro, it works fine when I use the interbak speakers. Now, if I connect to external amp and speakres with a normal 3.5 mm jack plug, the sound I hear is only the music but not the voice tracks? I would have thought the audio out connection would play the same as my internal speakers? I tried with both VLC and QuickTime and Perian 1.1 and I run all the latest updates. The auido plays back fine in both players with internal speakers, but with audio-out only the background music plays? Any idea?