I have two dedicated lines.It didn't make as big a difference as adding a PorterPort and PSAudio Power Port to them.But I do live in the boonies so not so much grunge on the lines.
Dedicated circuit
Wonder how many folks put in a dedicated line for their hifi. I added a 20 amp home run years ago, cost under $200 and the results were incredible. I swore off high priced power cords after that.