Reducing Resonance Between Speakers and Stands – Need Advice

FWIW, my KEF Reference, and in line with @mitch2 comment, were bolted to the stands. I think the goal is to make the speakers one with the stands, not isolate them, mass load the stands, and then dissipate any vibration using a good set of footers. 

Thank you! As always, you provide so much useful information.

For now, I will buy some silicone footers and use them between speakers and stands. I will also try to fill the stands with sand. In the future, I will buy better stands and use dedicated isolators instead of spikes. 

OP

I suggest that you use Iso Acoustic isolation devices. fir my personal observation, it is a must for me in mounting my Ls50 and ATCs on the stand mounts.

for me (YMMV) the isolators help enhance the separation of instruments and vocals of several singers. just makes a clearer soundstage that help projecting in my mind the venue.

try it, if it does not work for your needs, just return it

good luck

Symposium Svelteshelf and Aliexpress maglev footers work wonders on this problem. Somewhat less efficient are Symposium rollerblocks on their Svelteshelves

My suggestion with speakers like this is to focus less on spikes and more on preventijng rocking.  You want to minimize the ability of those speakers to respond to the force generated by the motors (drivers).  Given the right situation, distance from speaker to floor, weight, etc. the speaker if not the speaker and stand will rock back and forth, which causes the bass issues you are noting.  

My suggestion as an experiment is to put a cloth on top and add 20 lbs. and if you hear night and day differences you know hot to address the problem.