power cables with drains

If the cable is in the room with the speakers, its going to vibrate. Think about the poor cables INSIDE the speaker boxes...no toilet paper roll will save them! The only benefit to raising cables is it's easier to vacuum under them, but you have to really raise 'em...fishing line from the ceiling...yeah man...

Your first question sounds like an ’Almarg' or ’Atmasphere’ question’.
Those 2 guys know electrical stuff way beyond most mortals.
And, they are nice people, too.

As for the second question regarding lifting cables, some believe it helps isolate the cables from vibrations that diminish sound quality. My dealer says you can use anything (think toilet paper rolls) and get the same result as some of the more expensive options.
Though, to me, some of this gets a bit anal.
B