This is a feature that ML though well. After some time of no music at the binding posts, the sensing circuit shuts off the high voltage section that activates the electrostatic charge for full operation. Must of us, are just users, and we keep forgetting to leave unplugged the system and the speakers power cord from mains A.C. when we are not at the house. Leaving unplugged the power cord from the wall, it is the best way to protect them from any power surge. The panels will support the surge, but the power supply will not. But, usually there is no power surges, or problems with the main A.C., so the feature built in allow us to be protected of the debris and dust free. Remember that we, as ML user, should at least once a month, vacuum the stat panels, even that we have this feature. It is wise to do it. Happy listening,
Roberto.