Just a note here to clarify that the optical Toslink/SDIF format can only carry digital PCM or Dolby Digital or (plain) DTS. Basically your 5.1 channel original digital audio format varieties. The Toslink support on the Oticon TV Adapter is even a little bit more limited that it only either supports digital PCM or Dolby Digital. Its manual does not say that it supports the (plain) DTS format even though Toslink can support it.
So newer digital audio formats like Dolby Digital Plus or Dolby Atmos or DTS X, or any of the 7.1 channel digital audio variety can not be carried and supported by Toslink due to the Toslink’s limited bandwidth.
So if you have video content with one of the newer formats like Dolby Atmos, it’s not going to be able to output to Toslink to the TV Adapter anyway from your TV. Unless your TV has an option to “dumb down” the Dolby Atmos content to just digital PCM or Dolby Digital before sending out to the TV’s Toslink output connector, the TV Adapter is not going to see any signal other than PCM and Dolby Digital.
If you buy a third party box that intercepts the HDMI output from the TV and passes it through to the Dolby Atmos supported soundbar, and if this box has the ability to convert the Dolby Atmos audio into PCM or Dolby Digital to its Toslink output IN PARALLEL with passing through the Dolby Atmos HDMI to the sound bar, then you’re golden. But if this box, in the process of dumbing down the Dolby Atmos audio to PCM or Dolby Digital for the Toslink out to the TV Adapter, also has to send this dumbed down digital audio to its HDMI output port, then your soundbar is not going to get the original Dolby Atmos audio from HDMI that you want. So it really depends on the box. So if/when you buy a third party box to get a Toslink split out for the TV Adapter, make sure that the Dolby Atmos is intact in the HDMI passthrough output from the box, if the box can dumb down the Dolby Atmos to Dolby Digital or digital PCM to split that audio out to its Toslink output for the TV Adapter.