Most have apparently glanced over my response in January with a solution that doesn't involve buying an extra device to keep the HDMI handshake from renegotiating. Main issue is the Android TV is essentially an always on device, but it tries to enter a deep sleep at ~15 minutes that kills the HDMI handshake and apparently wakes itself right back up again. Anyway, there is an obscure setting that prevents the deep sleep, keeping the HDMI board always available, and preventing loss of handshake as if the TV were on, allowing the secondary device to work flawlessly.
Anyway, in Network Settings, enable Remote start. This setting keeps the TV always available so it can monitor IP traffic for an on signal from an IP remote. You may also need to enable IP Control under Network, Home network. It has been several months without issue now, so I didn't remember the exact process, but I believe these are the related settings and should work for all.
C'est bizarre mais ca marche. Depuis que j'ai fait cette manip ma barre de son ne s'allume plus toute seule quand la TV est en veille.
Pour les TV qui n'ont pas android je n'ai pas cherché, mais tu trouveras peut être la solution dans la communauté US/UK.
