Speakers on carpet over concrete

I use the spikes, not sure if I can hear a difference without the spikes.

It probably won’t matter but try it and see. I have similar floor. Speakers are on castors. 

Completely decouple, no spikes at all. I didn't think people still used spikes on speakers. I've had to dig up basements and fix water, add drains and repair or replace waste pipes. All the guys with stereos in there basements use pods or springs, now. I haven't seen spikes in 15 years.. Spikes transfer a lot of the bass into the floor and then into the walls. It  smears the bass signal and vibrates the house.. The same in a house, spikes setting on spring pads maybe. :-) Spikes not so much.

I been using Townshend Podiums for over 2.5 years, they sure work well.

Decouple with individual springs, properly sized for the weight of your speakers or Herbies Giant Fat Gliders or Threaded Stud Gliders. Size individual springs by putting the actual load somewhere in the middle of the usable range, and account for any differences in weight distribution between the front and back of your speakers since the front can be heavier due to the weight of the drivers.

For a very low cost, cut squares of Owens Corning 703 or 705 rigid fiberglass, or use hockey pucks. The Owens Corning board is very similar to what is used in the AV RoomService EVPs.

If you want to pay more money look at Townshend, RevOpods, IsoAcoustics GAIA footers, or any number of other popular products. Some like Nobsound spring footers, which are relatively inexpensive.

Thank you all for some excellent options.  I didn't think the bass would vibrate the house due to the mass of the floor.  I'll start with the cheaper options like hockey pucks.