Spikes or Spikeless

I also have a basement floor with carpet and padding. Over a 6 mo. to 1 yr. period I tried various combinations of spikes, wood plinths, rubber or composite footers, and nothing. This was for my VSA VR-4jrs. The worst was spikes directly through the carpet into the concrete. Grey, harsh sound with severely attenuated bass. What I finally settled on was a pair of custom maple platforms, 1" thick and about 2" extending beyond the speakers' plinths. Speakers spiked into the platforms, platforms spiked into the concrete thru the carpet. Got back my mid-bass, balanced out the rest of the spectrum, lost the harshness on top. I went with 4 feet on both sets of spikes but I have no doubt 3 would be better; also a 2" thick maple platform would probably be superior too. The platforms elevated my speakers a bit but luckily this did not cause problems re tweeter height and so forth.

I'm not sure what the objective is. Spikes are usually needed to decouple speaker from vibrating floor (infinitely small point cannot transfer energy). Your floor is concrete and most likely won't vibrate, so I assume you want to suppress speaker resonances. In that case you should couple speaker to the floor - either by direct placement on the carpet or on heavy base (thick marble or granite).

Spikes couple and allow vibrations to transfer. I realize that many theorize that spikes decouple by reducing the contact area between the bottom of the speaker and the floor. The reality is that the small contact point creates a very large psi value that in effect bolts the two components together. Vibrations travel very easily through spikes in both directions. Spikes are used with speakers to create a stiff, no rocking stance. All speakers are not the same so many times you have to try different things to find which works best for a given situation.

Wow - Someone put a lid on this open can of worms...=)
Thank you for all your input - I will give a few ideas a try: Im thinking try the Spikes to the concrete and see if that works. At 50# each I just did not think the spikes would "penetrate" into the concrete and perform properly. The idea of the spikes is to hold the speaker stationary. I was afraid they would "slide/vibrate" around. I will update on how much a PITA it is or was not...and my conclusions

I have a concrete floor with vinyl flooring and a rug over it. My Gamut L5s come on a base with 4 large outrigger cones; they also have cups for the cones to rest in. My two friends and I have listened to them several times with and without the cones resting in the cups and everytime we decided that they sounded better with the cups. YMMV.