This thing works quite well and is exactly doing what we expect from the mains filter. The meaningful test would be with several audio components connected to its plugs and mutually interconnected to make an audio chain. Especially if some of them use SMPS power supplies. This would show if there is an effect to reduce switching frequency intermodulations. The test with single component like DAC or preamp is meaningless.
But why wouldn't you contact the manufacturer and ask them if they have any documentation of this kind of capability, from the testing they have done? Shouldn't the burden of proof be primarily on the manufacturer to prove whatever they claim in their marketing stuff, and burden placed upon independent testers be limited to claims they have made that refute claims that had first been made by the manufacturer?
The thing is, it ought to sufficient for audio consumers to simply point out, when a manufacturer has not provided compelling evidence that the product actually does whatever it is explicitly or implicitly supposed to do, that the evidence that is required of them has not been provided. The job of someone like Amir should only be to validate the claims and evidence given by the manufacturer. Manufacturers often leave it for audiophiles to decide for themselves what a given product actually does, thus creating a situation where someone like Amir needs to come along and inform audiophiles that the thing doesn't actually do that. Then the audiophiles who believed something that drawn into question by Amir's tests get all up in arms. This is NOT the way it ought to be. Manufacturers should be expected to state their claims clearly and back up their claims by publishing their test results. And when Amir tests something and finds that it doesn't do what the manufacturer claims, audiophiles should expect the manufacturer to either admit that their testing was flawed or else point out the flaw in Amir's testing.
Thus, it seems to me that you ought to contact the manufacturer and ask for proof or evidence of the device's ability to isolate each output from the switching noise fed back into the box by other devices with switching power supplies.