My living room TV is attached to an ageing Windows box that we use as a media centre and middleweight gaming PC. To better fill the room with sound (I hate those tinny flat speakers they like to put into TVs these days! It automatically turns itself on when the TV turns on, but it turns itself off all by itself. My solution is BeepAlive, a little Go program that runs in a Windows system tray and makes a very quiet noise once every 9 minutes. Now, so long as the media centre computer and TV remain powered-on, the soundbar stays awake.