Just for the heck of it, I decided to go with TOSLink (which is basically the S/PDIF protocol on fiber) instead of the coax. I've never had a chance to play with TOSLink before. So I bought an optical cable and hooked it up. And once it dawned on me that the synth and the 828 can't sync if they're both on internal clock (duh), it worked fine. It's kind of cool to have a laser in your synth:
Here's a less artistic but clearer shot of the cable connector.
That little metal tip contains the fiber end. It looks round in the photo, but if you were to look at it closely it's actually D-shaped. The socket it goes into is also D-shaped, so it has to be rotated the right way in order to plug in.