Dual channel surround back power amp for 7.1 surround The AVR-587 is equipped with a total of 7 power amps including 2 for the Surround Back channel speaker to give you more clearly defined sound localization at the rear for 6.1-channel surround sources such as DTS-ES Discrete 6.1, DTS-ES Matrix 6.1, Dolby Digital EX, and DTS-ES NEO:6. Cinema Equalizer The sound from movie sources recorded in Dolby Digital, DTS or other formats empha- sizes high-frequency range due to a theater’s front speaker