If you can manage ripping the SACD into .dsf files you can easily play them from a computer into your separate DAC. If the DAC has a USB input that would be the easiest. Otherwise you ca get a USB to spdif converter. Bypassing the Denon and going straight to the DAC is the way to go.
Ultimately you may decide as so many of us have, that ripping all of your disks to a hard drive and playing them from a computer instead of from a disk player is the way to go for convenience and for SQ. Since you have JRiver, you're all set.
Of course going from the computer straight to DAC can be improved upon with many devices in between. I use a DLNR bridge, for ex.
Ultimately you may decide as so many of us have, that ripping all of your disks to a hard drive and playing them from a computer instead of from a disk player is the way to go for convenience and for SQ. Since you have JRiver, you're all set.
Of course going from the computer straight to DAC can be improved upon with many devices in between. I use a DLNR bridge, for ex.