I want to plug in an extension cord from the line out plug in the back of my iMac, then have it reach out to the front of the computer so it's quick and easy to plug in my headphones when I want. The problem, is that when I plug in the back, it will automatically turn off the internal speakers. But I want the internal speakers to stay on "audible" until i plug in the headphones on the other end of the cord. Any way to do this?