Dedicated lines do make a positive improvement, if for no other reasson to get the dimmer whitches out of the line, or to get the loose fitting AC receptacles and wire out of the front of the audio. Many homes are equipped with very low quality AC receptacles and they are fire hazards too. With regards to power cords, they are more hype than reality. Change something important like caps to v-caps or amps. A power cord is just a filter to change the sound, not necessarily more accurate or true. The only one I have heard to help digital was the Cardas Golden Reference in a high RF area and the noise was markedly reduced. In the absence of the nosie, it would not be needed. Spend money wisely, there is much hupe to "filter" it is your money, I like mine to do real good.