What isolation feet to use??

I would add that the theoretical ideal is to lower the resonant frequency below 5Hz, so that it becomes inaudible, but some devices, for example, may purposefully tune the resonant frequency between 20-40Hz, which will produce an audible bass hump (improve bass, increase dynamics).

Rakuennow: Marigo provides a money-back home audition period. Perhaps you have the engineering talent to take one apart and let us know how they work!

Honestly it really depends on your rack and the floor of your listening room (shaking wood flood or cement slab) and how your electronics were tuned.

In my system in my room (cement floor) coupling equipment to the shelves (maple)with spikes and the ayre myrtle cubes works best.

My recommendation is to play with home brew things and narrow down what improves the sound to you and then go from there.

Bubble wrap or a memory foam pillow will test isolation and wood cubes or large metal nuts directly under the chassis will test coupling. I second Herbie's as a source for cheap things to try. A big ziplock with sand under a component is also a quick and easy tester for whether your rack it self is the problem.

Take your time as I have found that different footers more often produces a difference rather than an 'improvement'.

Rakuennow, can you give an example of how you use that Sorbothane program? Looks like you have to input the footer size and that is what I thought the output would be.

Cheers

I have had great success with EdenSound Bearpaw brass cones and 2" Maple shelf .Also use a EAR Damping Pad between Bearpaw footers and equipment base...( Thor T1000 linestage ) ...

I've had excellent sucess with EquaRack products.