Hi @geo_man, welcome to the Sonos Community

While you can use the in-ceiling speakers in a wall, we would recommend using in-wall speakers instead. Placing the in-ceiling speakers in your wall will provide a less immersive sound experience as these speakers are designed to be downwards firing.

As both in-ceiling and in-wall sets are the same price, I would suggest going for the in-wall speakers for a better experience.

I hope this helps!

Thanks Jamie!  I since decided on a pair of the ikea picture frame speakers so I don’t need to cut my drywall.  Hopefully they do the trick. Best regards!

Hi

What is the intended application (i.e. home Theater, music listening etc.)?

How high are you mounting the speakers?

Hi. AjTrek.  Rear surrounds for home theater and music.  Unfortunately they will be high. Maybe 11 or 12’.  
 

I also have an arc and bigger sub. 
 

Hi @geo_man 

Unfortunately your intended mounting position is waaayyyy too high 

Rears should only be a maximum of 6ft above the listening position on a rear wall and 7ft on a side wall. The link below gives mounting positions for Sonos in-wall speakers. However the same applies for any in-wall or mounted speaker. 

The Arc and Sub will not compensate for exceeding the recommended positioning of the speakers; nor will TruePlay tuning.

https://www.sonos.com/pdfs/productguides/en-us/sonos_in_wall_by_sonance.pdf

This second link is a 3rd party review on using the iKea Picture Frame speakers as surrounds. While they can be used...the inference is that there are better choices within the Sonos line-up. The key phrase in the review IMO is “use them as subtle surround speakers”

Note: You’ll have to click through the ratings on the right of the review. Select “Videos/Movies”.

https://www.rtings.com/speaker/reviews/ikea/symfonisk-picture-frame

I disagree somewhat with the general consensus above. “Ceiling speakers” generally have round grilles while “in-wall speakers” generally are square or rectangular. “Best” in this respect is personal preference. Ceiling speakers often offer tweeters that can be aimed toward the listener. This is handy because the high frequency drivers tend to beam their energy and the adjustable angles can better accommodate the room layout. Some speakers will be shipped with both round and square grilles or grilles can be separately purchased as an accessory. The woofer, midrange, and tweeter in ceiling speakers are concentric while the divers in in-wall mount speakers are usually separately mounted in a rectangular frame. For regular box speakers there are some claims that concentric drivers are “best”. 

A problem with both ceiling and in-wall is that the “enclosure” is somewhat haphazard. For regular box speakers the enclosure is precisely designed to support the woofer, sometimes with a separate enclosed space behind the midrange. While there may be an enclosing box behind a ceiling or in-wall speaker, it is almost always too small to be effective. The most significant benefit of an included enclosure in the ceiling speaker is minimization of sound feed through to the room above and protection from falling debris and traveling “critters”.

Ear level or slightly above is generally the better location for surrounds, but the big mistake that I observe is locating the surround speakers too close to the listener. In this case listener position dominates. A listener located exactly at the midpoint will experience balanced sound, but a slight body or head movement will result in a significant shift in the sound image. A classic situation would be surrounds placed on end tables adjacent to a sofa. One speaker will dominate for a listener at either end of the sofa.

Thanks AjTrek and and buzz for your perspectives.  Cheers!

@geo_man 

Thanks for your THANKS!

However, it’s not my perspective. That’s why I provided links to Sonos mounting recommendations and the opinion of a respected 3rd party review. That said I wish you the best regarding your speaker choice and mounting.