My 17" Core 2 duo iMac has just suddenly stopped sending sound through the line out jack! The internal speakers work fine, but they are no longer disabled when I plug something into this jack, and no sound comes out of it! (no matter whether I plug in my powered speakers or headphones) I tried switching between my audio output drivers to "refresh" my drivers, but to no avail. (I have a usb recording console that the mac recognizes as a sound output device, though I don't have speakers attached to it) WTF?!