I have the Symphony IO. All I have to do is turn in on and sit down. It takes a few linutes, then you will hear the music sound richer and more open. Turn it off and music will just sound less engaging and open. This test is repeatable. I have basically the same system over 2 years and can tell changes good or bad. Very nice improvment whatever it is or does.
Add-Powr Power Conditioner Review
The owner of Add-Powr was doing business previously as QRT making a very similar product until he sold it to Nordost. The Add -Powr products are unique in that they upgrade the power in your walls, not just what you plug into them. This review is for the $$ flaghship product but they have many others on their website.
I use two of his products (one from thge QRT line and one from Add-Powr) in my system and the benefits are cumulative, here is the review of the "Sorcr" in hifi+