I am using the line-in on a Connect Amp for TV audio. The TV is a Samsung and the only source is a Roku 3. The audio and video are a bit out of sync, as expected, but the delay varies with the Roku app that is used. When watching HBO Now there is very little audio delay, but when watching Netflix there is much more, which I find irritating. Sling TV is even worse.
I’m wondering if the Sonos Amp can fix this problem. My TV does not have HDMI-ARC, so I’d have to use an optical to HDMI adapter for the connection.