Dick just got a 43" 4K M Series TV from Vizio, and he connected it to his Bose Soundlink Mini. But the remote does not control the volume of the sound going to the Bose Mini. His old Olivia TV had variable audio out, but the Vizio doesn't. When he went on Google, a lot of TVs no longer do that. Scott is using the RCA jacks to hook it up, so its an analog connection. Scott recommends looking in the TV's audio menu to specify whether he wants the volume to be fixed or variable. If that doesn't work, and he can only get fixed audio out, Scott would recommend using a universal remote like the Logitech Harmony, where the volume buttons on the remote would control the Bose speaker and not the TV.
43 inches is small for a 4K TV, however. Dick saw the 120" Vizio Reference 4K TV, which blew him away. But Scott says you almost have to build your house around it! It's $130,000, and they need to come do a site visit to see if the house could even accommodate such a large TV.