7.1 or 5.1

One simple benefit is that it can provide a more immersive experience. Like when a live audience applauds at the end of a performance, some clapping comes from the rear, helping to create the impression that you are in the performance hall.

During the performance, some echo might be audible from the rear, suggesting that you are in a large hall and some sound is reflecting off the back wall.

And of course for movies, the back channels offer the opportunity for sounds from behind, like explosions or the snap of a twig as someone approaches you from behind.

Sorry, I was away for a time, and I was not aware that Audiogon had become an "Analog Forum" or "Analog Room."

Was there an official declaration? Or did it just evolve on a de facto basis?

Ah. Thank you for explaining.

I have been accessing threads through Recent Discourse and never noticed the categorization of discussion groups. (I don't remember that we used to have such classifications.) I'll be sure to note this in the future.