I would think that your ide of running your cables under the carpet would be a bad idea, I would recommend along the wall, to where you want to drop them though the floor.
Your other concern as far as running cables next to ac wires, such as power wires.. I would not worry about that to much, the idea is sound as to why you should not run the cables next to the power wire.. the power wire is operating at 60hz, a constant 60hz, so the cable has a magnetic field constantly being created and colapsed around it, and this magnetic field could induce a voltage on near by wires, i.e. the speaker wires you are wanting to run…
In the real world, it wont affect your sound quality very much at all, a few options. Keep your speaker wire about 12 inches or more away from the power wire. Look for shielded speaker cable. If you can get shielded cable this will nullify the magnetic field of the power cable.
Hope this helps.
Also, I would recommend a long sleve shirt, and a light weight jacket, and jeans..
