Any experience with Harmonix feet

Agree entirely with Teck5. I am using RF 999-MT myself with dramatic impact; they proved to be a necessary addition after redecoration of the listening room.

Be aware, Harmonix themselves call these "tuning feet", so nothing to experiment with in a whim! You really need to audition these and it is advisable to talk to a certified Harmonix dealer about what may be the best fit product in your room with your speakers.

Just for the sake of additional information. Stone platforms, as suggested bw Teck5 may actually be a full-fledged option rather than someting additional. May I ask you, where you are located? There is a small local company here called Subbase Audio who manufacture brilliant loudspeaker platforms. Custom made only, they use slate, instrument wood and a mix of minerals (that remains undisclosed proprietary research, of course) in a variety of finishes at a cost that may be well below 2 sets of the big Harmonix tuning feet. (Don't know whether the latter still holds if they had to be sent overseas, hence my previous question where you live).) Anyway, these heavy platforms do not "tune" in any way, they stabilize the speaker and elimine detrimental influences to the highest possible degree, whilst at the same time optimizing coupling and effectively dissipating resonances. I have similar platforms for my amplification that work great.
http://www.subbaseaudio.de/
Sorry, no English version, to see the product, click Subbase écho LS on the left, on the new page there are thumbnails that will open a gallery when clicked

Hi Karelfd!
I believe Merlins Z-spikes are internally damped.
Using a platform from Subbaseaudio which is also damped I believe will be to much on a wooden floor with plastic foam underneath.
RF 999-MT from Harmonix are mainly for much heavier speaker than Merlins and will not work optional with Merlins in my room I believe (correct me if I´m wrong).
But thanks very much for your advice, like everything else it´s a matter of synergy.

A dear friend of mine will turn some feet made of bronze
tomorrow with a countersunk hole in the middle for spikes.
My present feet are made of Delrin and sounds ok. Curious if bronze will improve or maybe even the combination.
Unfortunately in Sweden, were I come from, possibilities of testing at home are very limited if not zero. In U.S. competition is much higher.

Have a nice day!

Would these work with carpet on top of 9 inches of concrete or would I be better off putting them directly on the concrete using 400 pound speakers?

Hi Husk01!
"Would these work........................"
Are you refering to Harmonix RF999-MT or what?

Clabe, Yes, I was referrng to the RF999-MT.