I'd like to connect my Macbook Air to my Home Theater system. I want to play movies directly from my laptop onto my large TV. I have the necessary mini display to HDMI cable. When I hooked it up, I got HD picture through the AV receiver but no sound. Do i need to connect a separate cable into my receiver to get sound? The receiver is a Denon AVR-3311 CI. Ideally I thought the HDMI connection could covey picture and sound into the receiver. Thanks.