Mark Levinson 380 Owner's Manual page 7

Caution! It is extremely important that all components in your
system be properly grounded. Under no circumstances
should you defeat a three-prong AC cord with a
"ground-lifter" or "cheater" adaptor, as doing so may
allow dangerous voltages to build up between
components. The presence of these voltages would
pose a threat to both your person and your
equipment.
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