Does raising speaker cables off the floor really make a big difference?

It didn’t make any difference with mine. Until I ran them across the ceiling. Attached to ceramic insulators used on the old high power lines. Everything opened up them. Clarity, transparency, and lowered the noise floor drastically. You must separate the power cords and interconnects though when doing the with them. Every little bit helps. Oh, I found Velcro from the ceiling works best with the power cords... who would have thunk... 

If the same degree of sensitivity that some people claim in their hearing prowess was declared in the other senses the individual would certainly be considered a candidate for psychiatric evaluation.  I don't think I've ever heard anybody claim to be able to see more clearly by elevating their lamp cord.  Or that the heating pad on their sore back emitted a better quality heat by rerouting the power cord.  Only in audiophilia does this psychosis exist.

Forgot to add I am running tubes. A friend running solid state found that having them from the ceiling with red and blue yarn worked equally as well. You must alternate the colors. And suspend the speaker wire at exactly .93 the total wall height for maximum clarity and transparency. After approximately 273.5 hours of break in you will achieve maximum soundstage and details. Also the edginess will smooth out.  

Not funny.

I mentioned the yarn to my wife she wondered which would work best, cotton, wool, acrylic, silk, bamboo, hemp, linen or a blended?