How do I get Roon to play through my Bryston DAC?
Its hard to say with so little information about what system you are running Roon on and exactly what Bryston DAC and how you want to connect to it and if you want to be able to play to other zones at the same time or not.
Have a read of this and see if this it you going or not. If not come back with more specific details and questions.
https://kb.roonlabs.com/Getting_Started
https://kb.roonlabs.com/FAQ:_How_do_I_set_up_Roon_to_use_my_DAC%3F
Do you have a Bryston BDP or pi