No 5.1 With Macbook Pro and Logitech Z-5500 Speakers

I recently purchased a Logitech Z-5500 speaker set. I've read that when using the digital output 5.1 should automatically be triggered by the applications with 5.1 capability such as iTunes, Quicktime, or VLC Player.

I can get surround sound to run in any of these applications though. Only the right and left speaker fire up, along with the subwoofer. Any ideas as to what should be done? I'm thinking something needs to be changed in Audio MIDI Setup... but I can't seem to figure out what.

Thanks.

 

Try PLII on the z-5500 audio controller.

 

Or here is a video:

http://www.youtube.com/watch?v=CdVgShuJlao

 

It will always come done to "defined settings" within the onboard Audio chip, e.g. I have 5.1 Surround Headphones but the Realtek Audio chip always defaults to "headphones" and I must therefore define my outputs through the RealTek HD Audio Manager before I get that "sexy" sound.

 

Thanks a lot guys. I got everything working. I was trying to change the effect when my music was paused so nothing would happen since there was input.