Ok, I bought an apple TV box and it works well with my ipad. I decided to try it with the imac last night and after a few pecks, it worked. This morning I turned on the imac and my headphones no longer work. All the sound is coming from the speakers not the headphones. I did something to change that but I don't know what. Can anyone tell me what I did and how I can change it back to so that my headphones will work? Thanks to all, Mike