I may have a possible solution to this problem. Our Denon receiver stopped putting out sound for no reason also. My husband called Denon and talked to a most helpful technician. All that was causing the problem was a buid-up of dust in the headphone jack. The technician said to my husband "I know this will sound crazy, but blow into the headphone jack as hard as you can." He did, heard something click and now we have sound. So simple, yet who would have thought of that? Hope this helps!