I am interested in this as well. I just bought my Arc system with the S1 surrounds a few months ago. And I am wondering if Sonos will offer a trade in for them against a purchase of a pair of 300s.

Lots of discussion about using Era 300s for rear surrounds.  In fact I’d say Sonos is pushing for them to be used this way rather than as a separate pair.  

But to answer your question, yes, the side and upfiring speakers will operate to provide additional atmos effects when bonded to an Arc or Beam Gen 2.  It’s being labeled as 7.1.4 audio, where your current setup is 5.1.2.

Sonos offers upgrade discounts base on older equipment you have, but not the One SL.  You could use the One SLs in another room or sell them if you’re past the return date.

Looking forward to some reviews vs Sonos marketing 

I have a similar question as I have just pre-ordered 2 x Era 300’s to replace the Sonos 1’s I use as rear speakers for my 5.1 set up.

Any Atmos content would be streamed via Amazon Music.

In the room, I currently have a Beam (Gen 1), a Sub (Gen 2) and the rears which will soon be Era 300’s. i.e. the Beam in my surround sound set-up is not Dolby Atmos capable.

Trying to put it simply, if I stream a Dolby Atmos source to the ‘room’ rather than just the 2 Era 300’s, will I still hear Atmos from the rears or will the audio coming from the Era speakers be ‘down mixed’ to standard 5.1?

Many thanks all.

Since the Beam (Gen 1) doesn’t support Dolby Atmos, you will only get stereo playback from Amazon Music. If you want Dolby Atmos music, you have to use the Era 300’s separately from the Beam or upgrade your Beam to a Gen 2 or an Arc.

Sorry to disappoint, but the Era 300s cannot be used with a Beam Gen 1 as surrounds.

https://support.sonos.com/en-us/article/surround-sound-guidelines-and-limitations

Era 100 can be used as surround speakers for an Arc, Beam (any generation), or Ray. Era 300 can be used with an Arc or Beam (Gen 2) only.

Many thanks for your reply, much appreciated.

Unfortunately, I purchased a set of era 300s as surrounds, I had hoped that adding them would increase the Atmos effect, and really give me  7 channel audio... But I am very very disappointed! I've turned the 300s up to +3 and the Atmos +3 and I can stand right in front of the 300s and try to learn sound, playing an Atmos track... There is no extra chanel that I can hear that makes 5 to 7... And although I can hear the Atmos effect from the ARC when I listen to the 3's the Atmos speaker I can hardly hear even with my ear near the top of the speaker. 

If I'm doing something wrong, I'd love to know, as I plugged my Sonos ones back in and had to turn the boosted volume back down to zero... And could clearly hear surround effects, again... I thought the sound buble would envelope me with these new speakers, but they seem like they are underpowered, or the volume is set incorrectly in the app. I am not looking for the surround sound to be too strong... But with my ones, when things fly from front to back... With the 300's things fly from front and then kind of fade to the back... They don't move through the room. Like I said, I can stand over the 300's and can barely hear anything, no matter the scene on the TV... So I'm just really disappointed. I've decided to return mine. I'm wondering if the 100's would have the volume of my 1's with better dispersion???  Just no extra Atmos effect... Really thought Sonos would have tuned the Atmos speaker to match the bar? 

Sounds odd. Did you remove the old surrounds and bond, rather than group, the 300s?

The other thing that might help is making sure you update to the latest firmware. I've heard that makes a big difference.

I found when I turned off true play they were much better, still have them turned up to 3-4+ they do have to sit behind and to the sides... angled on to the main sitting position. I believe I have the lastest firm ware. When I do an update says it is up to date. Does anyone know, when I turn up the Atmos effect, it makes it louder on the ARC, but does it do anything for the 300's? Seems like Atmos control for the 300's is really needed. And I CANNOT get it to do the quick true play on my android phone... It doesn't even show a true play option on my phone or tablet, at all? Only on iOS.

???

I have similar mixed experience. Using the Arc, 2 subs with 2 Era 300. Using Apple Music as recommended by Sonos. When playing ATMOS content I get a better special experience compared with my Sonos One’s which is expected. However the area where I get this experience is very limited and I have to sit near and between the 2 Era 300. Era 300 is not doing a good job in my opinion when playing stereo content. Unfortunately Sonos disables the front firing speaker when Era 300 are used as surround. I am missing the punch of my Sonos Ones in my room. It would be great if Sonos would give an option to control the front firing driver of the Era 300.

Also experience static pops from the Era 300. Sonos will replace them, still annoying.

The Sonos App/Firmware 15.2 software is buggy as well. Sometimes the surround is not working or the speaker is very quiet even though I used them a couple of hours before. Sliders in different screens on my iOS devices are jumpy and sometimes control other slides on the screen without changing them. Hope Sonos is fixing all these issues soon, because this is not what I expect from Sonos to receive beta quality software and hardware. Spending that much for speakers I certainly don’t want to be a tester for Sonos and expect premium quality and testing before a release.

Hi, I have similar references. I got my Era 300 last week and I found that the front speaker (voice) is too loud and you really can't hear the surround speaker. Also, I don't find the surrounding effects are not coming through. Sothe front area is too loud surround speaker doesn't provide any sound effects.

Would be interested in what the problem is. 

Thorsten

Hi. I replaced 2 x Play 5s with 2 x Era 300s linked to an Arc. I do see a difference - it’s subtle but I find Dolby Atmos much more immersive - it’s not the big dynamic change you get when you make your speakers a stereo pair, or a rear speaker set. But playing for example Morbius in Dolby Atmos, you hear all the sound of being in the ship’s storage unit - sound height as well as the lateral sound from normal stereo systems.

To install, I removed the Play 5 surrounds, and then installed each Era 300 separately and then set them up as surround speakers to my Arc. They didn't;t work at first - cutting in and out, and I needed to unplug my Arc to reset the connections before they worked. I’m very happy with them.

Hope this helps, and it is just a personal opinion.  

I purchased a pair of Era 300's on launch to replace One SL's to go with an Arc and a gen 3 and gen 2 sub. Installation was a breeze, everything paired up nicely and all updated fine. I had various Atmos demo's ready to try in Kodi on an Nvidia Shield Pro.

I tried a 7.1.4 test tone demo and was pleased to hear a difference between the surround and rear channels IE a difference between 5 channels and 7 channels then moved on to the Atmos channels the two Arc channels came through clear and I got a sense of height from them, with my eyes shut they sounded like they were on the ceiling, moved on to the Era height channels and disappointment. I could hear the speakers work but the sound was coming from the speakers not the ceiling. I expected a bubble of sound but this was missing.

I've watched various demo's and key scenes in films with Atmos soundtracks and they sound great, but…

They sounded great with the One SL's the Era's are £900 I wasn't hearing £900 of improvement.

I'm currently like you debating sending these back and sticking with the One's, or if I can get adaptors for my current floor stands maybe trying the Era 100's.

Wow. This is extremely disappointing news. Given the professional reviews, I convinced myself it was worth the small fortune to replace my rear Ones with Era 300’s. I think I’ll stick with my current setup. Thank you all for your honest feedback. Hopefully, Sonos has a fix?

I had the same result after my first trueplay run, it sounded like the sound was coming from behind and not above.

I redid True play while seated in MLP and that made am massive difference for me. 

I am extremely happy with the Era 300's as rears. 

Rewatching so much atmos content now. 

Sorry for my ignorance, but what does MLP stand for?

Main Listening Position.

Just purchased these speakers today, I did some testing after opening. 1 test being just using the sonos era 300 by it self, sounded great! Not as good as a play 5 (5 has a lot more bass and shoots in one direction, this speaker is not to replace the 5) but sounded very spacial!
 

Then I tested 2 sonos era 300’s together and it was pretty amazing. I thought it had connected to my sub as the bass was amazing and filled the room! 
 

I have have now put them as rear speakers (Arc+Sub) and I’m just a bit concerned with the loss in punch. I can hear the sounds coming from the roof along with the right and left side then from behind! My only concern is for the price and sound quality on their own, it feels like a waste as rear speakers. No bass comes from behind. Is this normal for rears? I used to have sonos 1’s so thought these might be a bit more heavier on the sound. I think I might return these only due to the sound loss on being rears! Let me know if anyone else has experienced this and how I can possibly fix it! 

I too have an Arc, a Sub, and a pair of One SLs as back surrounds. I’m thinking of getting the Era 300s but I have a question:

Can I add the Era 300s as rear surrounds & use the existing One SLs as middle surrounds or is that something that’s just not doable in a Sonos system?

Welcome to the long running thread that awaits the answer from Sonos. Don’t know when or if we will get a resolution.

Nope. You will need to either use only the Era 300s as the surrounds or stick with the One SLs.  You can only use two same-model speakers as surrounds.  FWIW,  I recently replaced my One SLs as surrounds with Era 300s and I am really enjoying them. Whether its worth the additional cost is going to depend on each individual’s use case.  I play a lot of Blu-Ray disc Atmos content and really wanted the effect of additional upward firing speakers.

Thank you for the insight, really appreciate it! I'll also be using them exclusively for Atmos enabled films, but still on the fence due to the humongous asking price.