Well, I also "hate" it when people don't do just a bit of homework before complaining. From company website which has a clear section for hifi:
https://zerosurge.com/audio-visual-home-theater/
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I read it before and took it with a grain of salt. It is purposely vague marketing to "puff up" the value of having an EMI/RFI filter. The distortion they are talking about is likely from an electrical component degrading over time. They talk of this on the website homepage.
Regardless, this is not the primary purpose of this device and they make no claims that it is a power conditioner.
To tell you the truth, I don't understand what would be said of a power conditioner that can produce a perfect 60 Hz sign wave, because from what has been shown on ASR, such clean AC power is not necessary and provides little benefit. So such a device would get a golfing panther because it does something well, but unnecessary? That's for another day.
This interview answers some questions, but opens others. I assume that this device has electrolytic capacitors which won't last forever, but for this duty, maybe they last longer. And don't understand the preference for low capacity MOV based surge protection.
The curve below is also interesting and looks desirable. I wish this could be confirmed, but understand why not. Perhaps some high frequency pulses at safe voltage can "test" to see what it does since it responds to varying frequency pulses (from interview).
Introduction: For optimum protection from surges and noise, the goal is to keep the surge energy from exceeding the normal power wave region. As the surge energy travels, the sudden rise of voltage (dV/dt) and current (dI/dt) is what causes the degradation of sensitive electronics. We will...
zerosurge.com