I have actually researched this before resorting to the Massive but the answers are incomprehensible or not relevant to my set up. The isituation:watching some, some but not all you tube or a streamed movie. The problem the sound coming out of my hi fi speakers is slightly delayed to the visual. The set up: a smart TV,an optical out that bypasses the TV speakers, feeding into optical in on my Marantz stereo amp. Doesn’t seem to be so bad on all you tube but is a problem on a lot. Some people say turn TV speakers down but these are bypassed in the settings.
Friends had a similar problem when trying to use TV as a slave screen to a laptop but I wouldn’t expect to have the same problem with a smart TV doing the streaming. Thanks