If I read their web site correctly it seems that they are simply filtering or "Cleaning the mains".
From their website:
"QRTs proprietary circuitry acts at the source of the problem, reducing EMF noise and RFI interference effects on the mains waveform, audio and video signals and it does it without limiting the voltage swing or altering the impedance of the AC supply. Which makes the job of your hi-fis power supplies and active components much, much easier and thats what you hear from your system or see on your screen. Use a QRT purifier and youll experience a lower noise floor, greater clarity and separation and increased dynamic range, qualities that are just as apparent (and measurable) when it comes to the color, definition and detail on your AV display as they are in the context of a really great stereo set up. The result? Greater overall musical and visual coherence, more stable perspectives, greater realism."
If someone knows how to do this without using classical EMI and RFI filters they sure have stumped me.
From their website:
"QRTs proprietary circuitry acts at the source of the problem, reducing EMF noise and RFI interference effects on the mains waveform, audio and video signals and it does it without limiting the voltage swing or altering the impedance of the AC supply. Which makes the job of your hi-fis power supplies and active components much, much easier and thats what you hear from your system or see on your screen. Use a QRT purifier and youll experience a lower noise floor, greater clarity and separation and increased dynamic range, qualities that are just as apparent (and measurable) when it comes to the color, definition and detail on your AV display as they are in the context of a really great stereo set up. The result? Greater overall musical and visual coherence, more stable perspectives, greater realism."
If someone knows how to do this without using classical EMI and RFI filters they sure have stumped me.