After dinner, Gretchen had asked me to push the TV and the stereo cabinet in the family room back to where they belonged. Before doing that, I wanted to wire up the surround sound. With a couple of optical cables from the basement and some help from Gretchen, that's done now.
Now we can send sound from the TV (optionally) to the surround speakers. And it's in sync. :)
I guess I was right.