iFi Audio AC iPurifier Power Filter and Noise Reducer (3 PACK)

These are great. They actually work better than the PS Audio Noise harvester. Active noise cancelling works really well. My background noise has dropped, especially where I had noise from microwave/dimmers on before.

nice construction, but little improvement on video, a bit more on audio

Unless you had very noticeable issues with you power supply, the effects won’t hit you in the face ( or ears). Having said that, i have one in my main power supply and one in each of my power bars and I do notice a difference. The sound is warmer/fuller, and yes, with no source playing and the vol turned up, there is no hum, not a noise can be heard. It is not a waste of money!