<font color='#000000'>My manual for the TX-SR601/TX-SR701 states:
"When you connect the speakers to the ZONE 2 SPEAKERS terminals, set the "Hardware Confing" setting to "Zone 2." In this setting, while you use the remote zone (Zone 2), surround playback will not be available for the main room (2ch stereo playback only). When you are not using the Zone 2, 6.1 playback will be available for the main room."
I have a TX-SR701, I do not use Zone 2 but I did play around with the settings. When Zone 2 is activated, only front left, front right, and subwoofer will operate in the main room. If you buy a reciever that has PRE OUT for Zone 2, you MIGHT be able to have mutlichannel operation in the main room and simultaneously have two channel operation for Zone 2; I'm not sure though. You should call the manufacturer or ask a reputable dealer. (The 601 does not have Zone 2 PRE OUT but the 701 does, it is also above your price range though).
The only use for digital output that I can think of is for connecting a recording device or a computer. I personally do not use it but I might use it in the future if I get a decent computer with a decent sound card.</font>