- You should change your speakerlayout in the Audio Midi Setup utility. The program is located in /Applications/Utilities.\
Select your audio device in "Properties For:", then click the "Configure Speakers" button. Choose "Multichannel". Even if these settings are correct, you should change them and click "Apply", then change them back and again click "Apply". This is important, otherwise VLC cannot reliably detect which speakers are connected.\
- Make sure your device surround configuration is not set to emulate surround output. M-Audio for instance defaults to using SRS surround sound emulation in multichannel setups. You should change this to "None/OpenAL".\
- You should change your speakerlayout in the Audio Midi Setup utility. The program is located in /Applications/Utilities.\
Select your audio device in "Properties For:", then click the "Configure Speakers" button. Choose "Multichannel". Even if these settings are correct, you should change them and click "Apply", then change them back and again click "Apply". This is important, otherwise VLC cannot reliably detect which speakers are connected.\
- Make sure your device surround configuration is not set to emulate surround output. M-Audio for instance defaults to using SRS surround sound emulation in multichannel setups. You should change this to "None/OpenAL".\