I have the Romulus Signature and have no issues playing DSD files from JRiver or Audirvana via the dac's USB input. Make sure you select bitstreaming DSD in JRiver, and delivery of DSD via DoP in Audirvana.
However, I have not been able to get DSD files to play via any of the spdif inputs (of course via DoP); I'm not sure if the problem is with the DAC or my Audiobyte Hydra X usb converter.