Hello Mr. Happy

I think the idea behind mounting speakers on spikes is to transmit vibrations from the enclosing structure into the floor. Although golf balls will elevate your sub above the carpet or floor, I don't think they will serve to transmit any forces from the speaker. Seems to me that because the golf ball is somewhat elastic (90 or 100 compression?) and provides equal surface contact area at both ends, they will simply serve to get your sub vibrating worse than it would if it just sat on the floor. Of course spikes will certainly make little holes in your carpet.

Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.