Apparently your Vizio 5.1 soundbar has a built in amplifier, so technically no you don't need a AVR. Read the manual from your soundbar in connecting your devices to achieve 5.1 surround sound from all your components.
Media room- LG 4K OLED EG9600, Pioneer Elite VSX-90, Samsung 4K K8500, Klipsch Gallery G28's, Klipsch Sub 12, Klipsch RS-52 II, Optik HD cable
Living room- Sony 4K 79XBRX900B, Onkyo RC-360,HTPC, Klipsch Reference R-62II, Rc52II,PS4
Gaming room -Panasonic ST60, PS3, Wii