Upsampling - what goes on under the hood?

I was trying out the different upsampling settings on my Rossini today and I was wondering what happens under the hood.
Playing DSDx1:

  • Does DSDx1 upsampling leave the signal untouched?
  • Does DSDx2 upsampling demodulate the DSDx1 signal and remodulate to DSDx2?
  • Does DXD upsampling convert DSDx1 to PCM and then upsample to 384 (which would be DXD)
    Dito for DSDx2 playback
    Dito for PCM playback
    In which format does the signal finally reach the Ring DAC? What happens between the say DSDx2 upsampling and the Ring DAC input?

The upsampling settings only apply to PCM data. With DSD there is no upsampling performed and the bitstream is passed straight through in its original format.

The Ring DAC itself uses a format called Ring DAC format which doesn’t correspond directly to any commonly-used encoding that you would see in file distribution.

Thanks, @Andrew
That clarifies things