Bluetooth audio system with 5 sattelite speaker with USB , SD card. Note: Please make sure to select Input/output mode as per effect required. In case of 5.1 original Input: select input source to "5.1" & Sound mode/output mode to "Normal". In case of 2.0 Input: Select input source to "2.0/ Stereo" & Sound mode/output mode to "Normal or Prologic" for "2.0 or 5.1 Prologic effect" respectively.