Curious. With dialog and two phantoms, any one of the optical input can be used. What if ALL THREE are connected but only one is active? Do they autoswitch? And what if all three are receiving signals? (Lol - yes, I know, a bit wacky question.)
I can't test that I have 4 sources into an optical switch into the dialogue - so only one will ever be sent depending on the source I select on the switch
But yes if you had dialogue, and both phantoms set to optical with autoswitch it would be an interesting experiment to see what happened!!
Maybe a new way of Djing / mixing songs together without a mixer
Remember that an optical input has to be assigned to a room in order to hear its' content and Spark (iOS version at least) only allows one optical input per room.
The Autoswitch function only appears to work when the source first applies a signal. For example if you pause a CD and switch to another source and then resume playing from the CD, the switch will not happen automatically. So always on devices such as a Sonus Connect don't really benefit from the the autoswitch feature. That is my experience.