Wool Felt Footers?

I was able to source one-inch thick wool felt on Amazon for a reasonable cost.  I used 3M tape to attach it to the bottom of the Zoethecus Z-slab. I like what I am hearing.  BTW, after my purchase, I believe the Vicuña at the highest reaches of the Andes mountains have now been shorn.  Lucky for them, summer is coming.

Yeah, EVA, 703/705 fiberglass, cork, and wool felt are all described by AI almost word for word as offering similar benefits related to vibrations and sound insulation:

"dissipate vibration energy as heat, acting as a natural vibration absorber...also lightweight, flexible, and offers good thermal and sound insulation"

In addition to the appliance footers linked by @kr4, for very little money EVA is available custom-cut in just about any shape, size, and thickness (link) for users who want to roll their own and experiment with different facing materials and sizes/thicknesses.  Add the similar benefits of Sorbothane and platinum silicone to the above materials and audiophiles have many low cost choices for vibration isolation and damping applications.

@hjdca - Yes, the ability to slide the 90’ish pound DAC out of the rack when necessary is appreciated!

@pindac - If I were to cut the felt into 3x3 squares to use as footers, a thin layer of cork adheared to the top might work great.  I would leave the felt alone on the bottom for the reason discussed above.

@gdaddy1 - I have tried those and found they do indeed work well.  Years ago, I used a small bike tire inner tube as an air spring - also effective but obnoxious to keep the right amount of air pressure.  

@pindac 

"Creating a Supporting Structure for the System and then working with support for individual devices will enable systems in use using the above influences, to be tuned to meet ones personal preference for how a Color is able to influence the end sound produced." 

I agree with your thoughts.  My racks are very solid and stable on their own so the supporting platforms and footers may provide nuanced variations or colorations reflecting the individual materials and design.  In the case of the heavy DAC where I have used the wool felt, there are two platforms under that DAC, the very stiff BDR shelf and beneath that the constrained layer Z-slab.  The wool felt isolates the two platforms from the stand.  I suspect the density and thickness of the felt material also influences the resulting effect.  The felt I used is quite dense and firm, probably similar to an F5 or maybe F7 (although the source did not provide the rating), and is a full one inch thick. 

The actual footers under the DAC are currently platinum silicone hemispheres operating within the suggested weight range, so those probably provide an elastic spring-like effect.  I may try different footers such as felt pads as discussed by @helomech or maybe one of the stiffer options from Herbies since I have quite a few of their products around here.  The footers that came with the expensive DAC were basically bog-standard aluminum footers you can purchase from Amazon so I am interested to hear whether other materials will have a different sonic effect.

@cbrez - hockey pucks are vulcanized rubber and many here have reported good results over the years from using them beneath speakers.  I like the idea of putting felt pads on the bottoms if you have hard floors, or to allow components to slide on their shelves.  3M double sided 9448A tissue tape or 3M foam tape would probably work to adhere the pucks to the underside of speakers, stands, or components.

Much of this stuff that companies charge big bucks for can be accomplished with everyday products but some are not comfortable experimenting and others like the finished look of manufactured products.

Even though I am utilizing multiple vibration damping measures, I have come to appreciate the effect of the felt (see below the two platforms).  FYI, your iPhone can measure vibrations and even calibrate and connect to remote sensors (link to AI answer).