The answer, in general, is that all digital outputs from an SACD must be encrypted in some way or other, at least if you play by the rules of the SACD licensing agreement. So, the relatively standard links that RW mentioned do this. In addition, there are the proprietary connection schemes of Accuphase and Esoteric.
There is no 'off-the-shelf' way to get and play with the digital information, except for the DVDUpgrades mod.
Kal