Speaker Cables and Carpet

I have a situation where I’m covering up my speaker cables with carpet to give a neater, cleaner look. It goes (from bottom to top): carpet, rubber matting, speaker cables, rubber matting, carpet. The rubber matting is there because I wanted to avoid interactions between the wire and carpet and figured that would help, but maybe not?

The issue I seem to be having is a decrease in dynamics. The drum slaps don’t seem to have the same weight and punch, although the system overall sounds pretty good with great instrument separation and soundstage (something I didn’t expect). The treble seems a bit tamed for some reason, but still pretty good sounding.

I’m wondering if the change in sound I’m hearing is from electrical interactions with the carpet and/or rubber. Perhaps one or both are robbing some energy from the signal in the speaker cable. Does that seem to check out?

If so, I’m wondering what my solutions are. One thought is adding more runs of speaker wire between the amp and the speakers. Is this called biwiring or shotgunning? I’m thinking that if the carpet is robbing energy, then I can make up for it by adding more copper and reducing resistance. 

But maybe I just need to get the cables away from the carpet. Are there any good rules of thumb for how far cables need to be kept away from carpet?