Dark Listener is a 3ds Max add-on that switches the listener to dark mode, with the dark theme enabled automatically on startup once the plugin is installed. Activation is hands-off: no additional work is needed from the user to turn it on after installation.
The darker background in the 3ds Max listener is easier on the eyes, which the developer notes can mean more relaxed eyes and less eye strain during late-night sessions. Because the setting loads on startup, the listener opens in dark mode each time without any manual step.
Dark Listener is listed here as free, and is currently at version 1.0.0, last updated in June 2023. It ranks 12 on the Autodesk App Store. For current licensing and download details, check the developer's page.