[rfeenstra]

Notice the power plug is 3 prong polarized, grounding the chassis to house ground.  I assume your ac power cord is 3 wire.  If so, you do not have a hot chassis.  I listen to mine regularly without an isolation transformer.  Meter measurements of the chassis confirm that the chassis at ground potential.

Edit: I tooka couple of measurements on mine with the AC ground pin floating. No AC on the chassis but there was some DC. As I watched, the DC slowly came down. I grounded the chassis for a second and the chassis then remained at near 0 volts. Reception was actually quieter with the ground attached.