InvisibleInk
Headphoneus Supremus
I'm not sure that is a real concern since most of the time it is plugged into a computer or other electrical device. Read this Head-Fi page for a good explanation.
https://www.head-fi.org/threads/ifi-audio-nano-idsd-black-label-tour-details-page-12-tour-participants-page-26-post-386.864211/page-45#:~:text=You can actually run it,USB port is always powered.
That's correct, but many of us like to go portable with ours, with devices other than computers. I use a couple of digital transports and a S/PDIF cable when I do it.