My thinking regarding jrlouie's discovery was that it might be possible to isolate the analog stereo input from the DSP entirely when a digital input is specified for active input, so that the DSP wouldn't get confused and do something odd. In that case, though, the analog connection would still be present and available for the record output and second zone. I doubt that a firmware change can allow digital signals to reach the second zone or the record outputs - that gets into some signal management issues that quickly involve hardware issues. Producing a digital stereo signal could potentially be done in parallel with the main zone's signal (which is often multichannel), but converting that separate signal to analog would require an extra DAC. On the other hand, intercepting the signal downstream of the main zone DAC's would require either an analog circuit to downmix multichannel audio to stereo (if that is even possible, something that I'm not qualified to speak on) or a willingness to discard center and surround channels in the second zone when the main zone is operating with a multichannel source. And all of that is just for the record outputs, when the signal in question is the same one going to the main zone - for the second zone, it gets more complex.