@blue_collar_audio_guy I would pay attention to what carlsbad posted. As an engineer, I can tell you that what he stated here is spot on correct.
From what you wrote, you are not isolating, you are coupling in a significant manner. Look at it this way, if you use spikes on a concrete floor, which is setting in the earth at least 6 inches, then the floor is reasonably solid and unmoving. Using spikes to set a equipment stand on that keeps it from moving about since the floor is not moving about. However, if you do the same thing on a wooden floor, say an older home where the floor joices are questionable, then you are coupling the floor vibrations into the equipment rack. Back to the concrete example, if the earth moves, so does the equipment rack.
When you decouple, movement of the floor, in my examples above, do not transmit through the equipment rack. In order for this to happen, you need to have something that "does not couple" between the floor and rack and also between the rack and equipment on it. Spikes couple, the flat disks they often sit on also aid to couple.
Carslbad suggested rubber, sand, or springs for decoupling, do follow that line of thinking. I can add to that a bicycle tube filled with air, Sorbathane mats and hemi-spheres. Consider putting sand in a thick sealed plastic bag.
Another option is layering. For example, pick up four Sorbathane hemispheres, set them on a hard shelf such as Maple or Oak to make a floating shelf. Set the floating shelf on your equipment rack shelf, then use four more Sorbathane hemispheres under your equipment that you set on the floating shelf. What happens here is the vibration energy transmitted from the equipment rack into the floating shelf is reflected by the ratio of the density of the Sorbathane and the hard shelf, then what little transmits through to the next layer of Sorbathane is also reflected by the ratio of the Sorbathane hemispheres and the bottom of the equipment chassis, typically steel or aluminum. The energy that is reflected back is absorbed by the Sorbathane hemispheres and covered into a small amount of heat, which is what you want.
If the equipment rack is also isolated from the floor, then you will have three layers of isolation. It isn't too hard to get 60 dB of isolation by using multiple layers. At that point, there is more vibration via the sound in the room than up through the rack.
And, yes, you can isolate the vibration of the sound as well. There are sheets of self adhesive materials, typically Sorbathane or something like it, which you can cut and stick on the insides of your equipment chassis. Look for automotive damping sheets that attach to the insides of doors and car body parts. Tube gear have high temperature O-Rings that you can buy to slide over the glass envelopes to squash the vibrations there as well.
Lastly, you can't over isolate your equipment from vibrations. What you can do is isolate so much that it becomes a waste of money to continue; money that can be better spent on better equipment, vinyl, or streaming sources.
