Subwoofer hum (grounding) from dac power supply?

[dance_with_plants]

so i got a new integrated and i do encounter some subwoofer hum, wich i think is a grounding issue maybe?
Chromecast Audio > smsl su1 > Kenwood KA3020 > Elac elx 8080 / svs sb1000

i was able to track down most of it tho and it has to do with my dac for the most part. as soon as i disconnect my dac, the subwoofer hum goes down a tiny amount that i wont even notice for the most part. i invested further and this is what ive noticed.

I have a hate relationship with 99% of usb charger plugs. i bought 15 of them and all of them create some really high pitch noise withing the plug, most people seem to not even hear. i hear it across the room tho. that means, i cant use them. the ONLY usb plug i,ve came across that is silent, is the one from my chromecast audio. in return, i had my dac hooked to my internet box usb port to power to not get that high pitch noise. turns out, when i have the dac hooked to the internet box usb, my sub hums like crazy. if i put the dac into the usb plug from my chromecast and put my chromecast into my internet box however, the sub hum goes away to a minimum. there is still some leftover but i think that has to do with the high level inputs to the sub itself and not with the dac.

1. what can i do to power that smsl without using a charger plug? are there any normal usable power adapters or something that provide better power while being silent?
2. for the tiny bit of rest hum, my amp does have a grounding screw on the back. can i do anything useful with that?

 

[amirm]

You can get a linear 5 volt supply for your dac. Cable boxes are huge sources of ground loops due to independent ground they often have. Avoid them as you did.