I have tried a number of them, even at shows. Most of them reduce dynamics or create overly warm, unnatural sound.
The best for digital is the VHaudio Plasmatron. It is not a filter or a regenerator. It is an AC voltage regulator. This actually improves the SQ of digital devices.
https://www.vhaudio.com/acpowerconditioning.html
Every exhibitor that auditions the Plasmatron in their room ultimately buys one. I did. It’s a no-brainer.
Steve N.
Empirical Audio