My speakers stands have spikes at the bottom. I read that spikes are to grab on to carpets. Can I keep them directly on tiled floor? Some people suggest placing a penny (coin) under the spikes. What would that do? I also read that spikes decouple speakers from the floor. Doesn't it actually couple it to the floor? Frictional Force can actually increase for spikes, which is why runners wear spikes shoes. Am I wrong?