Any Sonos speaker can be grouped with any other.  However, any speaker grouped with a TV source is going to be delayed by 75 ms, causing an echo.  You can delay the TV audio so they are in sync, but that can cause lip sync problems with the video. 

Thanks for the reply, but isn’t acceptable. Why would Sonos configure things like this?

Physics.  The delay for grouped speakers is for buffering in order to allow transport between floors/rooms.  Without the buffer, there is no way to resend bad packets when the inevitable communication error happens.  Even the surrounds/Sub are buffered, it’s just so low that it isn’t noticeable, and it requires a special direct connection, one-way 5 GHz private network to do it.  But that low latency connection is only good for line-of sight, so only surrounds and Subs use it.  Grouped speakers need the more robust buffer to make it work reliably between walls and floors

Your profile says you’ve been a Sonos user for 7 years or so. Have you been unaware of how sonos works in all that time? 
 

​@jgatie’s reply explains the buffering/delay. It is inherent in all Sonos streaming, with the exception of audio from tv to soundbars - which would otherwise cause terrible lip sync issues. But, the buffer then exists when playing the tv audio to other, grouped, speakers. 

“Your profile says you’ve been a Sonos user for 7 years or so. Have you been unaware of how sonos works in all that time? “

Thanks for the condescending reply. I assume you’ve driven an automobile for a given time? Do you know every bit of its engineering?

Up until now I have only used the Arc and Sub, never considering additional speakers. That is the reason for my question. 

If you have nothing constructive to add, please stay out of the discussion.

Update your profile. Currently there is no mention of the ARC.

As a test I suggest that you bring another SONOS speaker into the kitchen and Group it with the TV audio. Does the latency of the Grouped speaker bother you while watching TV in the kitchen?

An ERA100 can be used as a single speaker (a “Room), “Bonded” with another ERA100 forming a Room (stereo pair), or a two ERA100’s can be Bonded to a soundbar to build a surround Room. Latency is reduced (it’s still not zero) in a surround Room and most listeners are not annoyed by this reduced latency.

I forgot I even had products listed - thanks. Actually, years back I bought the Playbar and other Sonos components, but returned all of it when I realized my simple home theater separates cost less and sounded better.

It wasn’t until a couple years back when I tried the Arc, and it was leagues better than the older equipment.

So back to the subject at hand, I no longer have the Era 100s, as the salesperson told me I could just place them (singularly or in pairs) as an “extension speaker” for Tv. Never mentioned any latency issues.

You have to understand my living area / dining / kitchen are one big space. TV on far opposite end of kitchen. When we et b’fast at the kitchen bar, sometimes it’s difficult to hear the Arc clearly. If I placed the Eras where they would be located as surrounds, they’d span about halfway to the kitchen.

That said, as surrounds, would you hear the full range, or just ambient sounds?

Surround output is under the control of the film director. It could be wham-bang battleground effects, nighttime ambience (crickets), or nothing. One of my favorite films is strictly ambience surround. At first you might think that there is no surround, but if you disable the surrounds, the whole film collapses. This film should not be the user’s first surround experience because new to surround listeners expect to be smacked in the back of the head by surround effects. We’ve been through this before. Early stereo orchestra recordings often isolated left and right with a dense curtain. It was obvious stereo, but not very natural sounding.

In answer to your question: No, the surround channels would not usually provide full range audio for the kitchen. You could set the TV for stereo audio when you wanted to watch in the kitchen, but I suggest that this would soon become an unwelcome chore.

As a trial I suggest that you add a pair of speakers near your kitchen viewing location and experience the results. Give it a few days to get used to the environment. Some viewers (such as me) will be very annoyed by the latency, while others will welcome it. Sound is rather pokey, traveling at about one foot per millisecond. For live events in a large hall there will be latencies as the sound bounces around. The SONOS latency brings back the large hall live concert experience for some listeners.

In the end only you know what sounds “best” (to you).