Power conditioners and power regeneration

There are so many different options on this subject it’s unbelievable. But in the meantime it seems to me that between two companies that I’m comparing, they seem to do the same thing with power conditioning, and as far as I can tell there is no audible difference. Comparing two different conditioners, the elite 20 pfi and the aq pq2. On the other hand, I’ve heard that power regeneration is good, but it also can generate noise. Besides plugging into the wall, which I know works great, I still would like some protection to my amplifiers against brown out or surges. Has anyone else experienced any difference with these 2 products?