If the source you’re playing isn’t in 5.1, your Sonos home theater speakers will perform an audio up-mix of the stereo signal to create a simulated surround sound. This means you’ll still hear most audio out of the front channels, but the rear left and right surround speakers will play what is determined to be ambient audio.

If the ambient audio from the surround speakers isn’t loud enough, you can adjust the surround audio level in the Sonos app.

This is not the answer. Even if I adjust the surround ambient audio level, I often get only some backgroun d noise which is useless. 

My request is to have the option to hear the same audio on the rear as on the soundbar. 

This would be a benefit, because the rear are closer to the sitting position and when I have the same audio as on the soundbar, I can reduce the volume. 

Have you perhaps tried adjusting the ‘TV Level’ slider bar to +15 in the HT surround audio settings.. and try switching off TruePlay, which will allow setting the surrounds distance to more than 10ft/3m?

 That should (hopefully) bring plenty of the front TV stereo audio across to the two rear channels.

It’s a valid request. One that has been made repeatedly for years, unfortunately. 

Sonos doesn’t make a great solution for those who want this feature. I’m of the opinion that if they did, it would certainly assist a population of the ‘hard of hearing’ and others who need a secondary ‘voice channel’ that can be placed elsewhere in the room. 

I, too, ran into this issue many years ago with my father, where I wanted the full Dolby Digital experience, but he couldn’t quite hear the center channel very well. At the time, I was using the PLAYBAR, so I was able to introduce a headphone solution for him that was separate from the Sonos solution for me, but the evolution of technology has made that kind of solution more difficult, rather than easier.