I'm now set. I have the Toughpad sitting in its dock, USB television dongle plugged in… ABC News 24 running.
For sound, I ran:
`pactl load-module module-native-protocol-tcp port=<port> listen=<desktop_ip>`
on my desktop connected to the stereo, and:
`pactl load-module module-tunnel-sink server=tcp:<desktop_ip>:<port>` on the Toughpad.
I was then able to direct the sound from Kaffeine to the new audio sink that appeared. Latency and lip-sync is pretty good.
I'll have to keep this trick in mind for when I'm wanting to watch movies with decent sound.