I just set up these new speakers with my mac pro, and something just sounds wrong. The speakers overall aren't as good as I had hoped, but also, it just feels like there's something missing from the sound. I've put my ear to each speaker and there is sound coming out of every one. And I've also played around with the volume on the subwoofer. I'm wondering if maybe I'm not actually getting all the sound, because I'm only plugging them into the mini-jack in the back of the Mac Pro. I don't have an expansion sound card. Do I need to get one in order to actually get all the 6 channels? And if I'm not getting all the 6 channels, would that explain why it feels like I have ear muffs on when I listen to these speakers? Thanks!