I owned an early PS Audio PowerPlant for years! After a few year it became noisy with clicking sounds. I called about having it serviced. After a very rude conversation with someone on PS Audio staff I dropped it in the trash. Interesting by the time I got rid of it I'd upgraded my front end twice and never noticed a huge change. My front end at the drop was Mcintosh and Esoteric.
PS Audio PowerPlant 12 Review (AC Regenerator)
This is interesting. The testing concludes that the filtering inside of the actual electronics device is what matters and that this PS Audio product actually adds its own noise. Some irony.