I have a similar problem, with audio humming caused by several-different devices IF the 3-wire powercords are plugged into 3-wire outlets. My solution is as above--float the ground pin with some kind of cheater plug. While you're doing this, try to orient the remaining 2 wires to achieve the lowest voltage (measured to a grounded outlet centerscrew) on the chassis (with all signal cables disconnected). I've seen up to c. 60vac on a chassis when the remaining 2 sprongs are oriented the wrong way.
BTW, HUM from ground loops is caused by 60Hz AC-power current flowing between components thru the SIGNAL cables and somehow modulating that hum into the signal-carrying circuits. Understand that floating the 'green-ground' pin leaves some of that voltage previously drawn to some ground still on the chassis.
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BTW, HUM from ground loops is caused by 60Hz AC-power current flowing between components thru the SIGNAL cables and somehow modulating that hum into the signal-carrying circuits. Understand that floating the 'green-ground' pin leaves some of that voltage previously drawn to some ground still on the chassis.
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