LA Audio GCX20 - Manual (Page 12)

Page 12
In LINK mode Channel 1 meter displays the Gain Reduction for both
channels.
STEREO
switch
In link mode Channel 1 becomes the MASTER controller for both
channels. The Compressor controls, switches and leds on Channel 2 are
in-operative in LINK mode.
POWER
indicator
The blue POWER indicator is lit whenever power is applied to the unit.