Desktop top (or table top) EQ feature is designed to compensate for the boost caused by desktop reflection. We have chosen gain and frequency based on research of recording studios. Full paper is available here:
https://assets.ctfassets.net/4zjnzn055a4v/1GKiueHajGWaHntngcGy2K/6bb26d0fc6bd7f427de6ae0b9dc10804/2004_goldberg_makivirta_varla.pdf

In general, desktop EQ should be used if there is surface between the monitor and listener, like studio console or table. Best way to find it out is to measure frequency response of the speaker at listening location. Second best option is to listen with material you are familiar with. Do you perceive boost of the upper bass or low mid frequencies? Boost at this frequency range is perceived as warmth of the vocals.