Palmer Monicon White monitor controller.
The Palmer Monicon White is a passive monitor controller equipped with an input through a pair of unbalanced XLR combo connectors or an input through a 3.5 mm stereo jack and an output through a pair of combo XLR connectors or another 3.5 mm jack plug.
The unit is equipped with an attenuator pad, mute, stereo/mono switch and is manufactured in a solid white metal case.