The app otherwise is working well. I have Surface Pro 3 with Windows 10 of course. When I turn off the TV set or turn to another input I lose the Audio. The Steam still works otherwise and the audio returns once the TV set it back on. The Xbox is connected directly to the TV via HDMI no cable boxes or audio receivers hooked up.
Kinda defeats the purpose as I was hoping to use them when somebody else in the house wanted to use the main tv set.
P.S this app blows my mind what a time to be Alive :)