I wouldn't call the Absolute Sound review of the extension cord "very positive," but cables are not going to change your set-up as much as a new receiver/integrated amp. If your budget allows for $400 towards an amplifier of some sort it may be worth looking at an NAD, Cambridge Audio, Rotel, etc. Then you can use an extension cord for wire. Or go to a local hi-fi shop and get installation 14/2 for $0.50/ft. It is OFC, CL-3 rated, and usually the same ugly orange color as an extension cord.
Good luck!
Good luck!