Dear Bryston,
Considering that there is only a set of 5.1 analog inputs on the SP1/1.7/2, would it be possible to use say for example the tape or VCR left and right inputs so that the full 6/7.1 analog inputs are available? You could have it in the menu structure the same way that one configures the optical one and two inputs and then if one has 5.1 bypass selected, the SP would have the additional two back channels available.
Thanks,
l