my airplay sound quality is terrible

Hello Have a MacBook Air 2012 which I just installed Lion 10.8.2 on. Purchased the Apple TV so that I would be able to mirror my Mac on a Sony Bravia TV. I am using a HDMI cable from the monitor to the Apple TV box. The sound is aweful and the video is slow and breaks up. Is there some sort of setting I should be using in the display settings or is this even possible. Oh and by the way the only reason I bouth the Apple TV was for the mirroring because as many of us have said the mini HDMI port to HDMI on a monitor just out and out does not work period. Have called, emailed apple support third tier no help and been to the genius bar (where they have never heard of the problem) seriously? I brought up the links to the pages and pages on the support community, just so over the dear in headlights stare. Am I on a different planet?