Typically, you connect all your sources to your A/V receiver, then use the output from your A/V receiver into the One Connect box. You can go into Input 1 on the box, and just leave your TV on Input 1 all the time. This is what I do. I then turn on my A/V receiver and switch inputs inside the A/V receiver and adjust the volume of the A/V receiver. I do NOT use any 'SMART' functionality (Netflix/Prime/etc.) inside my TV. Instead, I use a Roku for that functionality, and the Roku is connected (surprise) to my A/V receiver.
I use a good universal remote to run everything so I don't have to use multiple remote controls.
Onkyo, Denon, Yamaha, Pioneer, and others all make very reasonably priced A/V receivers with good connectivity.
If you have an existing surround sound system with speakers throughout the room and a subwoofer, then you are already setup for much better audio than almost any sound bar is capable of delivering.