My toslink cable is a Wireworld Supernova 6 glass toslink, it goes into the toslink input of a Wadia 860x cdp (which in this case is serving as a digital "pass through") and then out via Kimber Select 2120 xlr digital coax to a Weiss Dac2 (the Weiss doesn't have a toslink input).
FWIW, Oppo has just replied to my inquiry, they say to use the analog stereo outputs rather than toslink. They say that way I can use the Dolby Digital TrueHD or DTS-HD formats.
But, you're right, I'll just have to try it both ways. I had assumed that by utilizing my outboard dac I would get superior sound. I'll have to try the settings for the analog outputs and see what happens.