This "electricity cleaner" performs very well according to TechRadar.

"Sooner or later, even the most sensible hi-fi enthusiast starts to wonder what sort of difference having a mains conditioner might make to the sound of their equipment. Mains electricity is the 'fuel' that powers your system. So it stands to reason; the cleaner the fuel, the better things should sound. But then doesn't the power supply in each individual hi-fi component deal with whatever impurities that might be present in the electricity supply?"



Link: TechRadar