I'm currently using the Rollerblocks Series 2+ double stacked under my Wilson Audio Duette speakers between the speakers and the stands. The stands are spiked on the bottom (from the manufacturer) sitting atop a Svelte Shelf.
The Svelte Shelf under the stand was a big improvement in terms of focus and cleaner bass. Adding the Rollerblocks double stacked between the monitors and the stands (in place of the brass tabs with magnetically placed points) really transformed the speaker into an entirely different animal all together. I was amazed at just how much distortion there was in the highs/mids/bass with the factory spikes.
The Rollerblocks completely changed the speaker into a very very refined and very resolute speaker that delivers a clean, and even delivery of the frequency range. The integrated presentation of the Duette is absolutely seamless like a single driver, but with out the single-driver-lacking in the extremes. And with out the single-driver peaks and vally unevenness delivery of its limited frequency response.
The highs are so clear and crystal, you will realize any weakness in your sytem's top end performance right away. The transition from the tweeter to the woofer is audibly missing, it is simply a very linear transition from highs to lows. And when you talk about lows, the bass delivery of the Duette is very impressive for what you get. The lowest octave is missing, but the roll off is there, and it's a very nice drop off. Now I get exceptional low end textures. The Duette has low end resolution I have never experienced before in a speaker.
Focus is crystal clear, tone is much more colorful and full bodied. Dynamics are in line with the linear frequency range delivery. Transient energy with each instrument is preserved. This translates to instruments being locked in such a presentation, that you can chose a single instrument within an orchestra and listen if you so choose. Otherwise, you can sit back and enjoy the entire orchestra, being able hear the difference between similar instruments among the various families of instrument types.
Anyone who owns a pair of Wilson Duette speakers should make it a point to get a set of double stacked Rollerblock Series 2+ to replace those magnetic-cones-on-brass-tabs that comes standard. They really sound pretty bad, but you won't know it until you try it, and then you'll see just how much further the Duette can go in terms of resolution and frequency extremes. But I'm sure they have the same positive affect on any speaker. Well worth the effort of trying for sure.