How do I play music from my Mac Pro through surround sound?

Question

My music currently is only playing from the front left and right stereo speakers and the bass. My mac pro is hooked up by a digital audio cable to my samsung home theater system. How can my audio play through all the speakers? It's important because trying to play music while I fall asleep only comes out of the front speakers, and not those behind my bed. I just got the new coldplay album and I need to figure this out!

Answer 1

check if your home theater system has a option like dolby pro logic II.  that would matrix the stereo sound to the surround speakers.