I have wired a optical cable to the digital output on tv, and expeted to route the audio output to an exteranl devices, but nothing happen, audio still goes out from tv loudspeakers,

2) i have many avi videos on usb hard drive, those video have 5.1 audio embedded on it but absolutely don t know how to hear them from tv, usually i use mac computer via an exteranl audio interface, but on tv always audio come out just on internal loudspeaker and cannot route them on digital output.