The 970 lacks a real second zone, so the implementation of a separate two-channel rig will take a bit of tinkering. The pre-amp outputs can't be re-assigned to provide a two-channel output, so you would need to either use a speaker selector switch, try something like using the tape output (which lacks a volume control) to feed a separate amp (or spare amp channels in a 7125 or 7700), or split the pre-amp outputs to feed the left and right signals to two pairs of amp channels with either a pair of y-adapters or a switchbox. There are some good selector switches from folks like Niles that might be worthwhile options for you, but I haven't ever used them.

The 990's second zone capability includes support for video output, but it can be used for audio only (I have a wireless speaker connected to my second zone). If you are seriously interested in multi-room capability, the 990 may be a better bet for you.