Like you, Nobrainer, I have a concrete floor covered with commercial carpet and no padding. A couple of years ago, I bought speakers with plinth bases (no spikes). Since my floor is not flat, the speakers wobbled. I tried using shims and pads to level and stabilize them, but I was not totally susccessful. In the end, I reached out to Sound Anchors. For $325 shipped, in about four weeks, they made me custom sized cradle bases with three-point adjustable spikes. The bases are solid metal and heavy, and fit my speakers perfectly. I noticed, after installing them, the very sort of improvements you are looking for: Cleaner transients, more stable images, and a slight increase in clarity. A great value.
So......what do you use under your speakers?
Looking to replace the stock spikes on my new speakers (Vivid Audio) that will make improvements in sound as well as give me a little more height. I have a commercial grade carpet over concrete with no padding. Not really looking to alter any frequency range but wouldn't mind general overall improvements in clarity, imaging, etc. I have been looking at Eden Sound Terracones, Stillpoints and Wave Kinetics. Price is not a deal breaker. TIA.