5.1 flac files not produce surround effect in my avr marantz nr1711

[sppmass]

last week i purchase marantz nr1711 when i play 5.1 flac files via usb it doest produce surround effect anyone help me

 

[Naturelover]

It's all there in the manual.
You need to read it
Your AVR can play only 2 channel from USB.