Mass-loading subwoofer

I just don't like the idea of either of those things. The concept is fine just use something that can't vibrate, or resonate. Maybe a rubber coated weight lifting plate. I think you can get one like 45kgs or more than one if you want. 

Some of the latest thinking is to isolate elements of the system from vibration and microphonics and there seems to be strong evidence for this. Consider looking into feet that isolate the subs from the floor rather than using feet that couple to the floor. This may accomplish what you are looking for in a different way.

Hmmm. Rubber-coated weights is an interesting idea too. 

The Auralex seems to already be pretty good at decoupling and especially for the price. An added benefit is that it’s much easier to move the subwoofer if needed. 
 

Something like Gaia’s would probably be better but also a good deal more expensive PLUS I really don’t want to have to remove the existing feet to replace? 

I was fighting with the set up of my sub and at the advice of some knowledgeable members here, I went completely against the REL guidelines. I moved the sub out of the corner (along the wall, approx 6ft. off the corner) and set it on a 1.5” thick granite slab…bingo. Problems solved. 

Jl1ny- Rel Special Carbon? That’s with a down-firing passive right? 
 

To be honest, I got the Auralex for my previous Rel (S5/SHO) which had the down-firing passive and it greatly improved it. I’ve never actually experimented without it with the G1 though.