In your article a DAC is considered a noise emitter and I would agree. Why then do you show it plugged in on the "clean side"?
Yeah, I honestly went back and forth, in part because some are powered by wall warts, but then the following point kind of became most prominent:
The DAC starts the analog signal, so it needs clean power.
If your DAC uses a wall wart, I suggest swapping it for a linear supply. If you get aftermarket power cords, shielded cords (which are cheap) are recommended to prevent radiating, and receiving noise.
As for dedicated digital cables... I'd have to see the specific item you are referring to. :)