I’m using this on my Tivo Bolt which comes with a 12volt ac/dc adapter commonly called a wallwort. These are miniature switching supplies which work well enough, but all switching supplies add noise to the output. This device is installed after the adapter and plugs into the Tivo. Voltage doesn’t matter, it’s a noise reducer.
It reduced the electrical noise and results in a better picture from the Tivo. It’s not an earthshaking improvement like a linear supply such as an Sbooster(but those are $300-$400) would be , but well worth the money. Recommended