I spikes are mainly used to decouple the speaker (in this case subwoofer) from the floor. Some people believe it helps in getting a better sound since you reduce the resonance from the floor boards etc. Some people say it helps if you live in an apartment since bass traveling through the floor to the apartment below yours is reduced. IMHO, your floors/ walls will resonate irrespective of spikes or rubber pads, that is why it is called resonance freq. If you hit high enough SPL it will travel through any acoustically untreated structure (dry wall, floors etc).


Behringer 1030A, SVS PB-12 Ultra, Etymotic ER-6i
PS3, SGT 10.1, Sansa Clip
Auralex