A:AnswerWorks perfectly well pairing with my Samsung 4K.
Voice sync is no issue. I use it with ROKU and volume is controlled by the remote. Not sure about DIRECT TV remote.
Be sure to select D.IN mode in Soundbar Source menu (right side of soundbar or its remote control).
A:AnswerSoundbars are completely separate speakers from the tv speakers, as long as the signal is making it to the soundbar (usually from the optical or HDMI ARC port in the TV) it should work.