which leads me to believe that the problem is more serious, and that it's a defect in my particular unit. Maybe the circuitry that turns off the the loudspeakers and switches the output to the headphone jack when a plug is inserted isn't fully switching over, and the hanging output is what's causing the problem. The load & impedance characteristics of the speakers/headphones as opposed to line-inputs, combined with the fact that there is no additional downstream amplification, might explain the symptoms.
