digital components such as dacs will ’sing’ along with the music, which is heard as noise and distortion. you can mass load your gear and change the frequency of the feedback noise, or you can decouple your gear and eliminate some or almost all of that noise/distortion. so much of what we hear as a digital signature is related to all the devices being affected by resonance. so this issue is a big deal.
stock footers are notorious for enabling feedback as they are an afterthought to the design.
the ultimate resonance control is ’active’ isolation; such as the Herzan TS-150.
http//www.herzan.com/products/active-vibration-control/ts-series.html
active isolation is 500x stiffer than any passive device such as a footer or shelf.....since it can stop and start. passive devices settle and float and overshoot. active devices do need a solid rack to be optimized, and soft floor or rack will compromise an ’active’ device. you have not heard what your gear can do until you’ve heard it on a properly installed active device.
I use 2 active shelves in my system.
but; active is expensive and more costly than your dac, so the next step is passive de-coupling footers. my favorite is the Wave Kinetics A10 U8’s which i use throughout my system.
http//wavekinetics.com/products/a10-u8/
a great thing about the A10 U8’s is that they do not change tonality, and don’t have that ’metallic/hard’ type sound that some footers impose on your tonal balance.
good luck with your dac.