It would be possible to a degree, but there are some caveats. First, I don't recall if the 990 passes digital audio inputs through the analog record outputs (Video1 and Tape) or if you would need to run analog cables from any sources you would want to use. Since I suspect the record out behavior is similar to the zone 2 behavior, it probably isn't a big deal for someone who already has zone 2 up and running. Second, the zone 3 output would be slaved to the main zone as far as active input is concerned. That may or may not be a problem for the outside speakers (or perhaps for the great room).