@RaydenSch 

As surround speakers I only would choose the Eras if I use Dolby Atmos. 
As a stereo pair I would prefer the Eras because of their double tweeters that imo can create a better sound stage. Also they offer the option for bluetooth and line in. 

No Atmos, the Ones as surrounds and the 100s for stereo.

Atmos exactly the opposite.

Why not Era100 for both in case of Atmos? Also for stereo imo they should be an advantage. 
 

Read the original question which asks the best way to deploy 2xEras and 2xOnes. 

@nik9669a 

Sorry… maybe I understood it in a wrong way. English isn’t my native language.

Thought he was asking for both speaker setups as an alternative for both usecase options. 

Agreed: Era100 replaces the One in Sonos’ lineup so anyone buying today would go Era. I think the Ones are at “last chance” for buyers. 

Thanks for your responses guys. Currently, I have my Ones working as surrounds. I want to setup a stereo pair and was wondering if I should buy a pair of Era 100s or try to find a pair of Ones somewhere. I have decided to buy a pair of Era 100s. I will test them as surrounds as well as stereo pair before making a decision on which one to use as a stereo pair for music. My gut feeling is that I’ll end up setting up the Era100s as surrounds because they will add 2 more channels or a wider rear soundstage, and some virtualization for the Atmos contents. I have already tested my Ones in a stereo configuration and I loved the soundstage, I love their front firing tweeters. It brings back the nostalgia of the stereo music that I grew up listening. 

Thanks!

Hi @RaydenSch 

I see you have made your decision so my input is most likely too late. I have a stereo pair of Era100’s and a stereo pair of Era 300’s both for music. I also have Era 300’s and Era 100’s in surround setups. That said I believe I have a pretty good understanding of how they are best used in different environments.  My next comments assume cost is not a deciding factor.

Surround

If you own an Arc using Era 100’s as surrounds is OK (as they will sound better than Sonos One’s). However, Era 300’s will complete the immersive sound not just for Dolby Atmos but any movie properly encoded with a surround track. To use the cliche’ car analogy...you shouldn’t buy a Corvette and use 87 octane fuel vs. the recommended 91 octane (or better) fuel if you want peak perfromance.  My (three) Arc’s all use Era 300’s as surrounds.

I also own a Beam2 that is also Dolby Atmos capable however, I chose to go with Era 100’s as surrounds. The reason is that the Beam2 is located in a guest bedroom connected to a TV with HDMI ARC input but no HDMI eARC input. Placing an Arc on that TV didn’t make sense and certainly not Era 300’s as surrounds; therefore the Beam2 instead with Era 100’s.

Music

I have a stereo pair of Fives in my main listening room for music. I’m a bit of a “stickler” for traditional stereo. However, I have a stereo pair of Era 300’s in an open space room that delivers great stereo with the added benefit of Dolby Atmos/Spatial Audio on selected tracks. It’s a win/win for what I call “non-critical” stereo music listening outside of my main listening area.

My stereo pair of Era 100’s are located in my garage which is 27 x 25 feet with 10 foot ceiling wall mounted 8 feet above floor level. IMO Era 100’s are great speakers and serve me well for casuals listening. In a smaller room of about 10 x 12 feet and normal room height of 8 feet they would most likely be outstanding. On the other-hand having tasted the “forbidden fruit” of my Fives and Era 300’s I most likely would not be satisfied with Era 100’s as my main listening hardware for music.

Subs: Home Theater

I recommend the following regardless of surround speakers:

Arc_Full size Sub

Beam 2_Full size sub or sub mini (depending upon room size)

Subs: Music

Sonos Fives x 2_sub mini (these are the only speakers IMO that sound great without a sub)

Era 300’s x 2-sub mini

Era 100’s x 2_sub mini.

Obviously, all that has been said is my personal opinion. The bottom-line here is to know your listening environment and where speakers will be used/placed. You may want to think repurpose use….can the speakers bought today be used elsewhere in the future. 

Thanks for sharing your experience. My basement rec room where I’m setting all this up is about 12 feet x 23 feet. At one of the two smaller walls I have an 85” TV with an ARC and Sub gen 3. The couch is kept right in the middle of the room and it’s facing the TV. Behind the couch there’s more seating area that’s kinda facing the other small wall which has a small bar and that’s where I want to setup a stereo with two speakers. I tested the stereo setup with a pair of Sonos ones (kept on either end of the short wall, so they were about 10 feet from one another) and they projected an amazing stereo image. If I install Era 100s there then I’m afraid that the outside tweeters of each will be projecting audio to the side walls and that’ll force me to either turn them towards the center of the room or place them closer to one another compromising the stereo separation. I will test them but I suspect a mono speaker with front firing speakers are best for my case. 
Era 100s however should work well as my surround speakers. Currently my surrounds are wall mounted behind my couch and on the long side walls about 6 feet from the floor and they are pointing down towards the center of my couch. I have flat 8 feet high ceiling. I’m getting good Dolby Atmos effects with my setup already. 
I’m not a big listener of 3D or spacial music, I find it fatiguing. When I want to listen to it for a bit, I use my existing 5.1.2 setup. So, never considered Era300s for music. Will not use Era300s as surrounds until Sonos improves their front channel separation or allow us to install dedicated front channel speakers. (Coming from a background of a true 5.1 channel system user). 
I had a Beam 2 before I had this Arc, and my biggest complaint was the poor front channel separation. Beam felt overpowered by my surrounds (Ones). At times that system gave me an impression of a 5.1 channel system that has the front left & right turned off lol. I’m afraid Era300s are going to do the same to an Arc, or true play will greatly attenuate the Eras to balance out the sound.

Sonos five would be an overkill for my case, hence, debating between Era100s and Ones.