Artikel: XGA series: what the ground lift switch does
XGA series: what the ground lift switch does
The ground lift switch on your XGA series amplifier is there to fix ground loops. A ground loop happens when two connected pieces of gear reach earth ground through different paths, and the result is usually a constant hum or buzz in your audio.
If you connect your Gemini Sound XGA amplifier and hear that steady buzz, engage the ground lift switch. It breaks the loop and clears the noise.