If you plan on playing two-channel audio only, and only through the 28s when you’re listening to them (in other words, the other loudspeakers in the house aren’t singing along), then one option is to get a reasonably-priced USB sound card with an optical digital output and connect that to the 28s. (This will require daisy-chaining the 28s with a second optical connection.)
You’ll need to be a little careful about how you’re managing the volume control – but this is not a big issue.
Of course, I’m ignoring the “network” part of your question – but if you wish to go that route, then an answer has already been provided.
