Question 5.1 sound system only working with DVD?

[Ragge]

Just installed my parents old 5.1 sound system and i just cant seem to get it working. I got it to work with an old DVD disk but not with the smart tv apps. I got the tv sound setting on external audio souce but it just wont play the sound in the speakers. Please help

 

[hang-the-9]

Would help to know this exact 5.1 setup model and how you have it hooked up to the TV along with the model of that.