Ok, I'll bite; why the WC connectors?
For one - the SDIF connectors used for DSD requires external clock. Each channel and clock are on there own seperate connector.
i.e. for 2 channels SDIF you need 3 connectors (1 clock, 1 channel 1, 1 channel 2), for 8 channels you need 9 connectors - if you are running multiple 2 channel dac's to decode 8 channel SDIF each dac would need to be using the same clock (possibly why there is a daisy chain capability).
This is the way SDIF has always been - go look at a PCM-2500b - using SDIF - there is clock, SDIF channel 1, SDIF channel 2
- Note that this is for SDIF (Sony Digital Interconnect Format) and not S/PDIF (Sony/Philips Digital Interconnect Format)
Update:
SDIF2 requires a 44.1kHz sync signal to be passed to the DAC and this should preferably come from the 1073DPD sync output via a third BNC cable. SDIF3 transmits the DSD signals with clock information included and should not need the sync signal.
Per:
http://www.ams-neve.com/Sites/8/Files/Documents/Outboard/1073DPA_DPD_User_Manual.pdf