WHAT HAS WORKED FOR YOU? ISOLATION PLATFORMS, FOOTERS, ETC. for a DAC?

What is reasonable to expect in SQ gain with respect to a DAC, since there are no actively moving parts?

Footers only? Platforms only? Or is a combination of both best?

Keeping this open ended (as well as budget wise) to see what Audiogon Members recommend and advise.

However, thoughts on Gains v.s. Spend with the specific products you are recommending are welcome and will be very helpful.

The only footers I have used in the past are those from Herbie's Audio Lab.  I have used two different 'audio' racks (which have been dismantled) and I am using their shelves as isolation platforms for my speakers and other components (but not the DACs).

The DACs in use are a Schiit Yggdrasil and an Exogal Comet Plus. The stock rubber footers with the Yggdrasil are as basic as they come; The Comet has an acrylic plate with rounded metal screws.

THANK YOU!