You are right @ millercarbon. My mistake. It couples it to the floor which is what Rel wants to happen. I knew Rel’s had a different approach. I just didn’t know how big the difference is. This may be the reason for poor reviews by some. I suspect that posting this tidbit will only give cannon fodder to the Rel haters.
From the article
https://rel.net/blog/2018-08-08/how-to/solutions-for-hard-floors/The cost of the Blu-Tack solution is extremely affordable and it works better than any other material. We do not recommend the use of spikes or platforms as they do not work well on RELs or any high-quality sub. Remember, the goal is to couple the subwoofer to the floor and transfer the energy into the room.
The more efficient the subwoofer’s mechanical pathway is, as is true with REL subwoofers, the bigger the jackhammer.
Platforms change the height off the ground (as do spikes) which will have a negative effect on the performance of your REL. The higher off the ground, the less bass will transfer into your room. You may well be surprised at how much better the sound is once this has been completed and for almost zero cost. Enjoy.