You can preview the contents of your Layer, Footage, or Composition panel on an external video monitor. This requires additional hardware, such as a video capture card or a FireWire port. If you’re using a video digitizing card to connect an external video monitor, follow the directions that came with your video digitizing card to connect the monitor for viewing previews. If you’re using a FireWire port, first connect a digital camcorder or video tape recorder (VTR) to the port, then connect the video monitor to the camcorder or VTR. For more information on setting up FireWire previews, see the documentation that came with your digital camcorder or VCR.
Whether or not color management is enabled for the project, After Effects does not manage the color of previews on an external video monitor. The colors sent to the external video monitor are in the project’s working color space. For more information, see Choose a working color space and enable color management.