…I’ve seen a few systems with these things or similar on top of them recently - reminds me of the Flux Dumper that HiFi News Magazine used to peddle in the 80s - I know Jimmy Hughes was a big believer in them, which brought natural suspicion!
You get a couple when you buy the artesania rack, that is being used in picture.
They are a damping device that just sits on the unit to reduce micro vibrations. They come in different weights. I have 2 and one sits on the dac, the other the clock.
The setup will depend upon the company whose room and setup this is. I would guess it may be Absolute Sounds. The reason I am commenting is to point out that what you see at an exhibition does not necessarily reflect a decision of the equipment manufacturer.