I was given one to use in my system and I did not expect to hear any differences and was going to send it back after hearing it. Well, 7 years later, I still have it in my system. It feeds an isolation transformer for my headphone rig. It does improve but the performance to value issue is one of the most contested in the hobby.
Do power cords make a difference?
I have a fairly sophisticated Home Theater set up with top quality components and cabling. I also have a 5 year old female Rhodesian Ridgeback named Lola. Last week I changed just the power cords to my processor and DVD player. Now every time a dog barks or an animal makes its appropriate sound, Lola jumps off of the couch (it is no easy feat to get her off of the couch) and tries to attack the dog or animal making the sound. This did NOT happen before. Motto of the story, yes power cords make a difference that even my dog can tell!!!