just to cover all the bases…
you might think about optical isolation. here, you can use fiber optic cables for ethernet data transmission from your NUC to the DAC. this will cleanse the digital signal of all upstream electrical noise and should, thereby, clear up the sound.
huge bump in SQ when i implemented fiber networking to my transport which is connected directly to the DAC via USB.
there are a number of threads here discussing this. here is a recent one but search around for others.