For me it's interesting to mesure a :
Furman AC-210 A E Power Conditioner
A professional product that has been proven for a long time and which is recognized as significantly improving the sound.
Not an "Audio(idiot)phile High End" product like this PS Audio Powerplant...
Proven by whom?
Testing these devices is, for me, like testing cables. The tests themselves are never particularly interesting because they always show the same thing: Device/cable does nothing meaningful, or it makes things slightly worse, with the slight asterisk "maybe it does something if your mains power is *really* bad". I can't imagine the Furman Power Conditioner would be any different.
Such testing is still useful though because it adds more ammo in the fight against nonsense and scam products.
The problem with these power conditioners, whether they're sold in good faith or as part of a scam, is that dirty power is
almost never a problem for audio gear. In this test, for example, mains noise isn't producing any measurable noise in the Schiit headphone amp's output, so installing
any device that purports to clean up or condition mains power isn't going to improve anything, because there isn't a problem to solve here.