There is only one way I can think of in which laying the speaker cables on the floor would have an effect on the sound. That's if the floor were metal, as you'd then have extra capacitance on the speaker line, which could attenuate the higher frequencies.

H-O-W-E-V-E-R....

You'd need many, many yards of cable laying on said metal floor to achieve any sort of capacitance value high enough to have any noticeable effect.

Two plates an inch square spaced 1 mil apart with an air dielectric result in a capacitance of around 225 picofarads. I'm not going to bother to work out what the capacitance would be on a typical run of a few yards, but it would certainly not be high enough to be of any significance when driven by the low-impedance output of the amplifier.

All of which is academic for those with normal wooden floors anyway. [Linked Image]