Ethernet (without using power lines) is best. Wifi after that and power line is absolute last. I believe the Ethernet jack on your cable box is an input though, not an output? If it is an output, you may need a router.
If you are too far from your router to run Ethernet, consider a mesh system like this one:
https://amzn.to/2LWWVm8
If your DAC is pre 2010 it really won’t sound very good with anything but high resolution files.
If you are too far from your router to run Ethernet, consider a mesh system like this one:
https://amzn.to/2LWWVm8
If your DAC is pre 2010 it really won’t sound very good with anything but high resolution files.