As Cadboy says, SACD does not output digitally. It is a restriction of the format - the only ways to get a digital signal out of an SACD player are to use IEEE 1394 (Firewire, iLink, or whatever other name might have been attached to it), HDMI v1.2, or I believe the latest incarnation of Denon's proprietary Denon Link. Firewire digital audio output is offered on very few SACD players and even fewer receivers or processors (although several processors offer Firewire inputs, most do not include support for actually using Firewire as a digital input). HDMI v1.2 was announced last fall, but I haven't seen any hardware yet that supports it. DVD-Audio suffers from similar restrictions, but unlike SACD it will output a downmixed Dolby 2.0 signal through the digital connection - SACD simply leaves the digital output dead, as you've discovered.
You can either run stereo analog outputs from the Sony to the 950 (in which case you might want to use the stereo bypass mode to keep the signal in the analog domain all the way through), or you can connect the six-channel analog output of the Sony to the 950's six-channel analog input. Or, if you don't plan to buy any more SACD's, you can simply ignore the whole mess and listen to the CD side of the disc.