And because this is a full service shop here.

You could also just get rid of the old DVD-NC875V and use the S590 for everything. It does support SACD playback and if you connect the player to the receiver via HDMI (and set the S590 to playback the multi-channel SACD layer from SACD discs), it will output a full resolution multi-channel DSD stream to the Onkyo receiver, which the Onkyo receiver will then decode just as easily as it decodes multi-channel PCM, DTS-HD or Dolby TrueHD.
That may be your best/simplest option.
-CB