Mass-loading subwoofer


I have a Rel G1 MK2 subwoofer (108#) that sits on an Auralex Great Gramma V2 platform (300# limit) and I think that I want to mass-load it.
The question is mass-load with what and, how much weight?

I’ve been looking at (for instance) a box of granite/marble slabs etc. from Lowe’s that are still in the box and strapped, or bags of steel shot from sandbags.com etc. on Diversitech pads.

Would those options “rattle” etc?

I know that the obvious answer is to experiment but I really would like suggestions first and there seems to be surprisingly little information on the subject anyplace.

 

Thanks!

bacchus1234

Thanks for the responses folks! 
 

I DO realize that Rel themselves dissuade against using a platform but with my current flooring it does seem to work better. 

Yes, it IS an expensive subwoofer but I paid less for it (used) than most other midline or even less brands would’ve cost. I have zero intention of changing subwoofers but merely wanting to experiment using others expertise as a starting point.
You are very correct about room acoustics though and would certainly appreciate any suggestions in that department. 

I sincerely hope that this response doesn’t come off as overly negative though and I’m merely asking for advice within the confines of my situation. 
 

Thanks so much! 

I have a 42 pound curling stone on my REL 7i. Not sure it makes any difference, but it looks good. 

… actually, I do think that it’s always good to get a completely different perspective from the way you are currently thinking so maybe I really shouldn’t limit advice at all. 
 

Thanks again! 

Ha ha! zlone that’s a unique idea but where would I go about buying that? 
 

What is everyone’s thoughts on the “bundled” flooring idea? If I remember correctly, a 50# bundle was about $60-70. The bags of steel shot were pretty reasonable too. 

For years I have been going to countertop granite and quartz 

and have remnants cut to size it’s 1-1/4 inches thick and many beautiful colors of nature even 7nder my dacs I use a bit of blutac at the corners 

even on some Loudspeakers , looks great and a 16x15 cost me under $200