Pressing "SELECT" and "MENU" on the front panel at the same time while the unit is in standby will reset it to the factory defaults. Be sure to write down all of your settings (input config, speaker distances, channel trim, ...) first, as it'll all get wiped out. But it only affects the CD input, right? If so, I'd hold off on the reset until I'd tried some other things first. In addition to the analog interconnects, there could be an issue at the player (assuming other sources aren't affected).