I believe using an optical connection to hook up the polk. Then tge appleCV tv box into an hdmi arc port.
Then go into thr e sound set up, switch to optical .
This should play anything hook up to the tv thru the optical sound output, which is the polk.
Now if you wear a hwaring aid, and spouse doesnt, you could hook up a blue toothvtransmitter head phone to optical, set sound to external tv speaker plus optical, both would get sound--each would have their own adjustment. ( no sound var in this config )