I have been having my new iMac for over a week and noticed some parasites in the audio when I've plugged in my headphones (tried different headphones just to be sure). It's like a highpitched noice that ocurres on random basis and changes in tone and intensity. I can easily reproduce this by playing with soundlevel with the keyboard, when bars are at the middle it is most audible. It doesn't occur with any particular application and exists even with only the finder running. What do you think guys, could this be a hardware issue? Should I contact apple? I am just a few days from the 14 day limit since I bought it and could therefore ask for an exchange.