Hey Williamtell - we'd not be able to provide support for 3rd party hardware, sorry. Best of luck though.
I have a modern tv set with HDMI ARC (audio return channel) and this allows me to set up my TV and devices incuding sound bar as this rough (very) sketch. What I do need to do is when I switch to the HDMI port my fetch box is connected to is to change the input on my sound bar to HDMI.
Have a try and if you want any further info PM me and we can arrange a more instant way of communication.