I had a thought. What about running netjack as a device and then having another jack client on a rPi in another room?
Alternatively, shairport as an output device and then another rune installation recieving it.
I can imagine having one server and a couple of clients all controlled simply by the device outputs configured in the .asoundrc file. The advantage to this is that it would suit other mpd clients that are able to control the sound device output.