Just letting everyone know, as of yesterday, there is a reflash available at the dealerships that add mute to the navigation system on 15 and 16 Legacy and Outback models. Some late model 16's had it from the factory. 15-205-16 is the TSB to reference if the dealer doesn't know about it yet.
Yay! Finally! Thanks for the info; will check on it with the dealer. I do not see it on the Subaru Tech site yet but hopefully the dealer can still find it.