Speaker cable lifters.

I prefer Lincoln Logs. Don't laugh, they can n

be built up just like Tinker Toys!

#toddsyr.  I agree!  Lincoln logs will absorb more of those nasty vibrations.  Be sure and finish them with a neutral sounding wax.

Tried them and they only made it easier to dust the floor. They look neat but I am on a concrete slab with wood floors, did nothing for sound. But hey they may work for you. In comparison to other suggestions (fuses and the like) Tinker Toys, Lincoln Logs and wood blocks are cheap.  

The concept of cable "lifters" has an interesting history. They were apparently first proposed by Enid Lumley, a reviewer for TAS. This link adds a little more to the story:

https://positive-feedback.com/audio-discourse/bunking-cable-lifters/

It's a relatively inexpensive tweak to try. If you hear a difference in your system, in your room, with your ears, then that's all that really matters.

The OP has a high level system in what looks to be a challenging space.

Are room acoustics- damping/diffusion fully addressed? The ceiling/speaker arraignment has to be affecting overall SQ?

Leaning forward and eye squinting will probably have the same effect as cable lifters. Naturally-YMMV.

Expanding on wolfies comment- the entire room floor needs to be on a Minus K isolation platform for "true" vibration elimination.