I reviewed these feet at:

https://www.hifiwigwam.com/forum/topic/145382-isoacoustics-gaia-loudspeaker-feet/ as a result of my good audio buddy Kevin Fiske telling me about them. I thought you would be interested in his views.

As others have observed, the speaker/room interface is more complex than it might at first appear.

Spikes were long thought necessary to stop speakers from oscillating fore and aft in obedience to Newton’s Third Law as the driver cones pump back and forth. They were also assumed to conduct away undesirable vibration in equipment racks and so forth. Now some manufacturers are inviting us to accept that using spikes or any other form of coupling was the wrong approach all along.

The argument goes like this: spikes transfer energy from the speaker into the floor, and can cause it and the connected building structure to sing along with the music. Concrete and timber floors ring at different frequencies, but this unwanted accompaniment always lags behind what the speakers are producing. The speakers themselves, and the kit table, they are excited by the delayed, returning energy, resulting in a smeared, phasey corruption of the original signal.

Canada IsoAcoustics is a proponent of de-coupling. I borrowed a set of its Gaia I isolator footers to try with PMC MB2se speakers. At circa £1200 for eight, they are suitable for speakers weighing up to 100 kg, Other IsoAcoustics models at different prices are designed to work with lighter and heavier speakers.

Gaias are not merely Sorbothane pucks in fancy clothing. They are a patented design using multiple specialist gels with specific Shore durometers that are mechanically contained within a non-ferrous metal shell in such a way as to resist deflections while providing bi-directional isolation tuned to be effective right across the audio band for objects of a given weight range

The Gaia base has a soft concave cup that grips smooth surfaces such as tiles and wood, while the top is threaded for bolting directly to the underside of the speaker or stand base. Optional gripper cups allow the footers to be used on carpeted floors. The Gaia 1s are 64 mm in diameter, 49 mm high, and come with four alternative sizes of fitting bolts. As can be seen from the picture, they have a quality look. I was careful to achieve an identical above-floor height to that provided the MB2s’ factory-supplied spikes. The fitting process is fiddly: the footers are directional so need to be secured in the labelled orientation. Satisfying this key requirement while achieving plumb speaker side walls and a suitable tilt towards the listening position was not easy the first time around, but I got better at it.

After fitting the Gaias I noted that the sofa, on a thick wool carpet over high quality underlay on a screeded, insulated beam and block concrete floor, was no longer vibrating on bass-heavy passages. The bass was still present, but mostly as air pressurisation only and, not only that, but much cleaner too, tighter, better timed with less bloom and overhang. Tonal quality was more easily appreciated by listeners.

As IsoAcoustics has it, distortion from the floor imposes on both speakers nominally equally, and therefore appears centrally in the sound field, obscuring sound staging. In my system the Gaias released a greater still sense of 3D-ness and placement resolution from the MB2s. At one point I thought that with all the disruption and sweat of fitting the footers that I had fluffed the re-connection of cables and got the PMCs out of phase, but no; the Gaias not only pushed the distant wall of the sound stage even further away for a greater sense of depth, but on some recordings they extended it sideways too, outside of the left and right speaker axis.

Web Page: https://isoacoustics.com/products/gaia-series/