Usually a global switch. Enable this only if you are using condenser microphones. The XD Effects Engine The XD series is famous for its Dual Digital Stereo Effects Processor Dual Engine:
Users can choose from various presets including Hall, Room, and Voice Reverbs, as well as Echo and Pitch Change. Montarbo Xd 66 Manuale
, a "historic" 12-channel analog mixer he’d scored for a steal at a local market. It was a beautiful piece of Italian engineering, but it was currently silent, and he was missing the one thing that could bring it to life: the Usually a global switch