The two dedicated circuits are a great start, however, all power coming off the pole will fluctuate (by how much is anyone's guess). The farther out you are the more likely you will have greater fluctuations in voltage. I have not used a voltage regulator/line conditioner (if I had the cash I would) without any problems. A quality surge suppression is needed for any system, I would suggest either Furman or Tripp Lite, Furman just released an affordable line of power centers for home theater use. If you are worried about voltage drops and spikes then buy a regulator...It is a small amount of $$$ when the entire system is at risk. You can buy or borrow a clamp on AC/DC DMM and you will be able to tell the voltage changes on the lines.