The tape outs and the audio outs of the video inputs are active at all times but like zone 2 will not convert digital to analog. If the signal arrives in a digital format it will be sent out the optical out and if it arrives in analog format it will be sent out the tape outs and video outs. Most receivers work that way because they would need an additional set of DACS to do it otherwise and that would add to the cost.
Even if you did use one of those outputs, you would not have volume control and the main speakers would still play. The headphone out is really your only choice.
As an alternative you could probably use the variable audio outs of the TV.