I just ordered an AudioSource SW-15 (front-firing) sub as part of my first HT system. I am having brand new berber carpet and a carpet pad installed on top of the concrete slab in my basement. The carpet is not especially thick. Do I want to put spikes on this sub? Or just put it on the rubber feet it came with? Or directly flat on the carpet? Would spikes damage my carpet or carpet pad, or concrete? I also read somewhere else that spikes on concrete can cause some chattering sounds. Thanks for any advice.