Hi Dave,
I have a furman HDS-6 with 4 HR-6's that I use with an 896 and it works fine, although it is a bit soft for folks who have very loud instruments (drummers mostly). You hook the HR-6's up to the main unit in sequence with a pair of RJ-45's. The main unit has 1 stereo in and 4 mono ins. What I do is take a stereo pair off the 896 and run it to the HDS for monitoring the already recorded tracks (via a send off the mains in Sonar) and then use the 896 software mixer to send the players their tracks. I've taken one output off the 896 and run it through an outboard FX module so that I can dial in some reverb or whatever to one performer (usually the vox).
All in all, it's a pretty good system that is inexpensive....there are some better setups out there, but the ones I've seen begin getting very pricey very quickly.
Good luck
Dean