No way to get TV dialogue out of surround speakers

That makes no sense and isn't rooted in reality. The speakers have no trouble playing dialogue, of course. Just not when they're configured as surround speakers. 

And there you have it: when set up for the intended purpose, you can’t -whether intentionally or unintentionally- make the sounds emanate from the wrong source. 
 

If you were to set up a pair of speakers positioned near your viewing position instead, and group them with your Beam, this too will probably not work for you. Sonos is a multi-speaker, multi-room system designed to enable synchronised music play across the system.
 

To achieve this a small time delay is introduced when streaming starts, to give a buffer. With tv input to a soundbar this buffer is minimised to reduce lip sync issues, but Grouping Beam and another room/set of speakers, there will be a delay to the room speakers, resulting in an echo effect. You might find this acceptable; you might not. 

Is this a semantics discussion now? Technically speaking the speakers could do dialogue over surrounds. But the programming does not allow them to, just because they are surrounds. So the end, rooted in reality, is they can’t do dialogue.

I think this is drifting too far away from the point. Sonos, for TV playback, doesn’t have a setting for speakers setup in surround sound configuration to be used for something other than surround sound.  That means that they will play the surround audio as intended by the source material.  If there is no surround audio, they essentially play nothing.  They never play audio that was intended to play from front audio channels by the source material.  Sonos doesn’t do any sort of custom simulation of audio in the rear channels that was never intended in the source channel.

I don’t see it as ridiculous that Sonos uses the surround speakers as intended by source material.

That said, it seems reasonable that some people don’t want surround channel audio, but do want additional stereo or mono speakers playing TV audio beyond what the front soundbar or Amp provides.  This could be to personal hearing issues/preference or just because the room or space is large or open area...outdoors for instance.   This is pretty similar to what Sonos already offers with non-TV audio source.  You have the option of stereo playing only on the front speakers or playing from all 4 speakers...where atmos audio plays as intended from source.  So why not offer the same feature for TV audio?

As far as configuration goes, I think you could have just 3 options for the room.  Surround speakers always play surround audio channels only.  Surround speakers play surround when it’s in the source material, otherwise play stereo.  and always play stereo.

Just guessing at a couple reasons why…

• Dialogue might not be as clear as anticipated.  The front speaker setup has a center audio channel, either real or simulated with the amp, which handles most of the dialogue.  Obviously, no center channel in the rear, so dialogue would need to be handled differently.  Maybe the same simulation the amp does, but maybe not.  Not sure it would work as well as you think, but maybe just direct stereo in the rear is good.
• The feature may lend itself to misuse and a poor experience.  Surround speakers  are communicated to via private 5Ghz network, and works good in most situations with speakers placed in the expected location behind the seating area.  If you aren’t using them for surround, just additional front speakers, then you would think you could place them anywhere, maybe even a different room.  That would have negative consequences on trueplay tuning and wireless performance.
• It may lead to additional feature requests that Sonos wouldn’t be able to meet.  More volume control for example, or perhaps just a single ‘surround’ speaker instead of two.

I personally would be interested in the feature, just because I think it would make the amp a much more useful device for large spaces.  Say you have an outdoor environment with a TV.  Being that each amp can connect 2 pairs of outdoor speakers, a setup where the ‘surround’ will always play stereo for both TV and music sources means that you can setup 4 pairs of  passive speakers as a single Sonos room for that space.  If using the Sonos outdoor speakers that allow for 3 pair per amp, that’s 6 pairs.

‘If Sonos insistently filters dialogue out of surround speakers’ as others have highlighted SONOS do not remove audio from the Surround (and or overhead) channels.

Will you want surround effects played through the Front LCR when there is no active dialogue?

What you could do is put in a Feature request for an ‘all speaker’ stereo mode similar to what Yamaha and others provide in AVR’s.

All, I truly appreciate the discussion my post has prompted, and y'all have awakened me to the fact that Sonos may have reasons for limiting speakers set up in a surround configuration to playing only surround channel outputs. I appreciate that too.

I think Danny's and Joe's responses are most on point and seem to confirm what i had thought (which admittedly, i could have said nore nicely at the outset): that is, Sonos could be asked to enable different performance out of the surround speakers, ie a basic stereo playback on all speakers, so when we're viewing something that has no sound sounds anyway, we can still get some use and performance out of the other speakers, e.g. helping with louder broadcast of dialogue.

I'll make this feature suggestion. Or maybe Sonos reps check these threads.

I’m in agreement. Wish the surrounds (era 100s) could have some dialogue setting to help me hear the words from movies!! Thanks OP for posting.

if anything, Sonos should do this for accessibility, not all people have the same level of hearing. 

The only option for surround and rear full audio option would be to add 2 more speakers and have a separate room (like ‘living room rear’) for the speakers you want full sound out of. And then just combining the rooms when you want full rear audio

But be aware, if you group any other Sonos ‘room’ with a home theater ’room’, there will be a light delay between the two, but only when playing the TV’s input. When streaming directly, there will be no delay at all.