I thought spikes are used to transfer vibration to the floor?

I have a cement slab floor in the room my sub is in, and it sounds very dead. I've read in other places that rasied wood floors are bettter for subwoofer performance because the floor helps to radiate the sound. My LFM-1 sounds a lot better at my dad's house w/ raised wood floors vs. my slab floor. He has essestially the same system driving it as I do. So, this whole concept of isolating the sub from the floor seems counter to the whole wood floor vs. slab floor issue.

Maybe in a very live room with lots of reflective surfaces the isolator is desireable?