I am using a Chord Qutest with the R Pi 3 version with a HiFiBerry hat on and it works well. I mostly use ALAC (lots of resolutions) from my NAS, but have a bunch of DSF as well from SACDs I ripped and they play correctly as well. I use optical and coax and both work fine. I usually playback from Synology Audiostation rather than Rune, but I am trying to use Rune some more directly.
I am running the 2018 build build of Rune. Sometimes, I have to reboot to get back on the network. Other times (once a month maybe), it seems to get hung on DLNA or Airplay, but a reboot fixes it.
Seems like the GitHub commit is way old, so I can't build a more modern version of it. Other than one person, it seems like no-one else is updating it anymore either. It would be nice to know security updates are up to date at least since it is a WiFi device and will have the same holes the rest of the world has on it.