When I first connected my 17s to my moment (? March last year) the Moment interface notified me that it was updating their software. So, it seems there is some mechanism for connected products to keep the speakers up to date.
I have been told by a B&O technician that the TV (they are now connected to a BV14) updates their firmware but not the entire update package and that the only way to ensure you have the entire update is as already mentioned here.
That is, via technician with service tool or Transmitter 1 loaded with appropriate software.
Would be interested if anyone had further info on what the TV or Moment can update in the speakers...
Cheers
Scott