Quadraphonic 4.0 Surround. ⓘ Blu-ray Audio (BD-A) requires a blu-ray player. Dolby Atmos discs require a Dolby Atmos-certified soundbar or a Dolby Atmos-compatible AV Receiver. Dolby Atmos mix will ‘fold down' to 5.1 or stereo if a Dolby Atmos decoder is not detected.