Russ Andrews' 'Purifier' accessories are all shunt-connected mains filters: that is, they sit connected to the mains supply and effectively 'suck' the interference out of it without coming between mains and audio equipment. Many experimenters have found this approach preferable, though there are so many variables in specific designs that it may be dangerous to generalise. We looked at the Ultra Purifier some years ago and have also investigated the much cheaper 'Silencer' which implements some of the same ideas.



Link: TechRadar