ART Pro Audio CoolSwitchPro - Isolated A/B-Y Switch - Manual (Page 7)

7
PHASE
This switch allows you to invert the phase of the signal to the
OUTPUT B jack. This function is only available when the
TRANSFORMER ISOLATE switch is in the ISOLATE position.
When the PHASE switch is in the 0 position, the phase is not
affected. In the -180 position, the phase is inverted.
GROUND LIFT
This switch allows you to break the OUTPUT B ground
connection from directly connecting to the other ground
connections. In the GND position, OUTPUT B's ground is
connected. In the LIFT position, the direct connection is broken
and there is only an AC signal path to ground.