Proper Cable Placement.

Keeping power cords (and power filters) free from any kind of vibration, as may be induced by the floor, will make a huge difference. Try it out.

I bought some of the wire clamps from Pure Note to keep my cables apart. They sell 5/16" and 3/8" diameters. See their speaker cables to get an idea what they look like:
http://www.purenote.com/speakercables.htm

Eric what was your perception of cable performance using the Pure Note wire clamps. ?

I don't think I've ever heard the interconnects affecting each other.

Two things I do hear a difference, first of which, is when separating the red and black sections of speaker cables and separating digital and analog cables. To separate the red and black sections of the speaker cable, you just have to use separate runs of cables. If you are bi-wiring, use a single stereo channel for both the hot and another set of cable for the neutral. This greatly adds more coherency and smoothness in my system. I don't have this set up now since my new speakers have a twisted pair of CAT5 both internally and externally. I might upgrade to separate runs of OTA cables. The other thing I can hear a difference in is separate all cables that are analog and digital related meaning the powercables and interconnects. This is not as perceivable and might just be my brain doing tricks on me.

Darrylhifi:

I also use the Pure Note clamps and they do not alter the sound in any way. They are simply a wire management device to keep the cables neat and away from other cables like power cords.