Spikes or rubber feet.

Agree, these are Aerial Acoustics. This is my second pair. The cabinets are rock solid. The rubber feet are from Aerial Acoustics. But, they are fairly hard.

I have Aerial 7t’s. When I first got my speakers home I called Aerial and talked to Michael Kelly about this very issue. He recommended that I use the spikes since my floor was not a slab but a floor with joists over a basement. Once I found a good spot for the speakers I put the spikes on and never looked back although they are on carpet.

If the rubber flexes at audio frequencies,  the cabinet will also vibrate enough to smear the image. 

I tried out the differences between spikes and hard rubber pads, also due to oak hardwood parkett flooring in the past. 

The difference with my Burmester 961 speakers (35kg each) was so great that I *had to* go with spikes and that fiddly setup with those dimpled protector disks.

The spikes in these situations are seriously inconvenient but due to the very clear sound improvement a must, as far as my experience goes.

I now could organise two round, polished and baffled granite disks (reshaped from kitchen top cutout left overs) and place the spiked speakers on top of these.

This works really well avoiding floor damage even on tiled flooring.
M. 🇿🇦 

Alternatively, if you are on the ground floor cut a speaker sized hole in the floor, pour concrete into the bare dirt(might be best to excavate a bit and frame it)and viola a perfect pad for your speaker to sit on. Wooden floors nearly always move.