Answer from Parker612 on 5.1 surround on macbook pro:
OUTPUT SURROUND SOUND FROM YOUR MAC: (simplest way)
(*Check first to see if your Mac is capable of outputting surround sound through the Mini Displayport. Most models before early 2009 are not able to output multi-channel audio)
http://support.apple.com/kb/HT4241?viewlocale=en_US
- Use a Mini Display Port to HDMI cable and connect the HDMI into the Blu-Ray/DVD HDMI input on the receiver and the Mini Display to the Mini Display Port on your Mac.
- Go to System Preferences on your Mac. Click on the "Sound" icon. Then in the "Output" tab, select SONYAVAMP - HDMI
- Then go into Applications > Utilities > Audio MIDI Setup. On the left side of the window select HDMI. On the right side it then should say "Source: SONY AVAMP"
- Click the "Configure Speakers..." button in the bottom right of the window. Click the "Multichannel" tab. Then select "5.1 Surround" from the pull down menu. Click on each speaker to provide a test tone to make sure each is connect properly. Then click on "Apply"
- Last set is to go into the DVD Player to test it. Go to "Preferences" and click on the "Disc Setup" tab. Under Audio at the bottom of the window select "Digital Out - SONY AVAMP" from the drop down menu for "Audio output" *You now have 5.1 Channel Surround Sound from you Mac!