I’ve not used Power Plants before but from Paul McGowan of PS Audio’s videos, the Power Plants do not reduce AC Noise. In fact, he even corroborated Audio Science Review’s finding that Power Plants actually increase noise!
Paul describes the benefit of Power Plants being that the sine wave of the AC power remains stable despite the transient current demand from an amplifier connected to it - in short, it lowers impedance of the power supply, which he argues is more important than dealing with noise. The AC sine wave remains perfect even if the amplifier is demanding a lot of current.
In this manner, Power Plants do something entirely different than conditioners or isolation transformers (Torus etc). Paul argues that such devices succeed at removing noise, but at the expense of increasing impedance rather than decreasing it.
Paul’s explanation does make me wonder if Power Plants make any difference for connected source components, given that they won’t be drawing dynamic and transient current like the amplifier. Maybe someone that knows more than me can explain. I’m simply summarizing Paul’s explanation.
