Stillpoints Ultra SS vs spikes on concrete

Pretty hard to get solid concrete to vibrate in the first place. Are you worried about itty, bitty, tiny-tiney micro vibrations that only bats might notice? Speakers by there very nature are designed to work in their respective environment. The spikes IMO, if properly set-up should be most sufficient. Save your money and make sure that your source and pre are well isolated from unwanted vibes.

I would make sure your spikes are actually penetrating the carpet and sitting directly on the concrete. I used a sharp pointed X-acto hobby knife to make a small "X" so the spike actually sits on concrete. It made an obvious improvement.

Like the SS Ultras, have a set under my speakers, and they were a real improvement coming from spikes on a suspended wooden floor (with granite in between). That said, a good solid spike into concrete is a real solid (pun intended) solution. I'd be a lot less quick to assume that the Stillpoints would be an improvement under your circumstances (and, personally, I likely wouldn't have bothered had I concrete to spike to in the first place). At root, they provide a fundamentally different approach -- coupling and mass-loading v. isolation -- and which might work better in your particular setup may be unknowable absent some experimentation. If you're really itching to find out, try a set from an outfit with a lending or return policy (used The Cable Co for mine, ended up keeping them) and send'em back if they don't do it for you. The ultras are mighty spendy for a footer, makes good sense to try them out first if you can. If they can't convince you, consider yourself lucky and spike away with confidence and abandon. No?

Ultra a little better than cones/ risers. A very big dissapoimtment for me. Another mk2/SE marketing BS.

Spend $$$ on source.

A surprise for me...I have Vandersteen 5A's which have spikes designed for them...my speakers were on the spikes with brass floor protectors under the spikes. I moved into a new house with Travertine tile over congrete. Much to my surprise, on some frequencies, the whole speaker which is VERY heavy resonated uncontrolably...I could feel the speaker jumping up and down at these resonating frequencies. I fixed the problem after lots of experimentation by simply putting a bit of Gorilla tape under the floor protectors of the spikes and the speakers are sitting pretty. You never know what you bump into with this hobby.