Hello, Before I start I want to say that I know that the z906 kit has a very poor sound quality and is trash for a home cinema. I have had this kit for 6 years now, used it to get 5.1 sound for my PC and would like to recycle it now into a home cinema before buying a proper sound kit. And also that I'm not an expert in home theaters. I bought a 4k Sony TV (54.6" Sony KD-55XE7096) and set up the Logitech z906 and also mounted the satellites to the walls. I'm using an optical cable to connect the Sony TV directly to the Logitech z906 backpanel. I would like to get 5.1 sound. Here is a diagram : https://imgur.com/iaun1GF The TV has a built in Youtube button and when I go on Youtube and test the sound with a video like this : https://www.youtube.com/watch?v=PqVCPE8_ntE the speakers don't react like they should : - when FL and FR play, all speakers are used - when center plays, only center speaker is used - when RL and RR play, all speakers are used - when LFE subwoofer plays, nothing happens When I play a Netflix 5.1 program and select in Audio the 5.1 language, the RL and RR speakers don't seem to be working as 5.1 speakers. I've been trying to find out why it's not working, and I'm pretty sure for some reason that I'm missing something. I checked in my TV options and have the Dolby Digital set to Auto : https://imgur.com/xU9EZ6j(I can only chose "AUTO" and "OFF") Do I need to buy a reciever ? Does the sound need to come out via ARC HDMI from the TV ? Do I need something like a "Optical to 6 channel" unit ? (https://imgur.com/ovYmZKa ?) Is having 5.1 possible with my system ? Thank you for all your answers, I am very grateful.