Zapped, the audio equipment shouldn't care what voltage the signal ground is with relation to the earth, just so long as it's all consistant between the equipment and all components are using it as a ground reference. That "ground" might be 120VDC from the actual earth, but you'd never know unless you happened to touch it...
If that ground happened to fluctuate with the AC signal though, as I'd expect to see with a bad earth ground, yeah, there would be an annoying hum.
[This message has been edited by SteveFehr (edited 11-21-2006).]
