I'm opposed to multiple lines unless your power demands need it. They increase ground loops, which increases different types of noise. "Ground loops, I don't have those" yes you do, but they aren't bad enough to be noticed. All equipment has minor loops, it's just how electricity works.
What I recommend is using twisted in wall cable from JPS. If you HAVE to use multiple lines because you have 10amp amplifiers in mono, so be it.
Power conditioners are kind of another topic. Generally speaking they can have outputs for power amps and signal stuff that are different because of different power demands.
BTW Gander, that isn't how it works. Having your stereo on a different line is highly preferable. It all ties into the breaker box but noise won't go to the breaker box and then back out to your gear. It will however screw with the stereo if it's on the same line trying to get back to the breaker box.