I agree about not using spikes on a wood or composite floor, however if you have a pored concrete floor with carpet & pad overlay and properly spiked speakers, the floor is not going to absorb the bass. By using long enough spikes so the tips rest on the slab and the speaker cabinet bottoms are raised high enough to clear the carpet surface. You will have a solid, stable connection to the floor. Make sure you have sharp spikes and they are long enough.
Speakers on carpet over concrete
My system is current located in a partially finished basement. The floor is thick carpet over a thick pad on top of concrete. Does it affect performance of the speaker differently if spikes are used that pierce the carpet and pad, contacting the concrete below versus removing the spikes and having their "feet" resting on top of the carpet which is also a bit less stable? I'm sure I'm not the only one with a system installed on carpet over concrete. How are yours set up?