I would go a different route personally.  Most importantly, wireless audio gets much less reliable when you add a lot of bodies in a room, as you will in this restaurant.  You’ll get working well in an empty room, then get lots in interference when you add people.  There is also the issue of needing power outlets for each of the speakers in the right location, and where patrons can’t mess with them.  Also, the audio is going to be louder for patrons sitting close to the speakers, although 3 meters high should help with that.  You should set these up as separate rooms, no stereo pairs, as mono is better application here.  Trueplay tuning isn't a big advantage here.

Have you considered using Sonos amps instead?  If there is an existing system in place, and the speakers are of good quality, you could just replace the existing receiver/amp(s) with Sonos amps as needed.  Add volume control/speaker switches if needed.  You will still be able to control it via the Sonos amp, and probably fewer Sonos rooms over all.

As suggested, Sonos Amps and Sonos Sonance speakers would be a good fit. A single Amp can drive six of the “Speakers by Sonos and Sonance“ ones.

Architectural: https://www.sonos.com/en-us/shop/architectural

Speaker FAQ: https://www.sonos.com/en-us/shop/ceiling-speaker-pair

I also prefer using AMP’s.

A rule of thumb for this sort of space is to distribute ceiling speakers uniformly at about 3m spacing. This will yield a nice “wash” of sound. Normally, one would not attempt to distribute stereo audio, but if you do, alternate L/R such that each seat has a nearby left and right rather than having left down one side of the room and right down the other side. Make sure that you can independently control Volume in the areas, either by using separate SONOS AMPs’ or in-wall Volume controls.

If your goal is simply to supply background music, SONOS could work fine. If your goal is to incorporate microphone paging or augmenting a live performer, SONOS is not designed for this.

Thanks for the responses.

Power and connectivity aren’t an issue here as the speakers will sit on the overhead tracks. Both power and full cat5e connectivity exists which should negate those concerns.

I hadn’t considered the amp solution as suggested by all commenters (thanks to everyone).

it’s equally simple for us to run new speaker cable in the same overhead track. This issue I would now need to overcome is the speaker mounting/options.

With the proposed plan, I was thinking I’d be able to just sit the speakers on the tracks, up out the way. With ‘ceiling speakers’ I’d need a solution to mount them in a pod of some sort. The actual ceiling is another 1.5-2m (1m in the lounge area) above the track and has pipe work, extraction, ducting etc there. See photo!

Back to the drawing board

You’ll need to aim the speakers down, toward the seating area. Speakers emit high frequencies in a cone shaped pattern and the apex angle of the cone tends to decrease with increasing frequency. If you simply sit speakers on the tracks, most of the highs will remain above the listeners. 

I can’t recommend any specific brand, nor have I used any before, but this seems like a good application for pendant speakers.  Should be able to hang them from the existing tracks, and blend in nicely.

Mounting suggestions:

https://www.sonance.com/in-wall-in-ceiling/visual-performance/accessories/visualperformanceseriesacousticenclosures

Not rocket science, you can crib dimensions from these and knock out your own particle-board copies cheap too.

For legal public music services, check out http://sonos.com/business

Thanks, we have a 3rd party business streaming service we use.

Hi, 4 months have passed. Please share your experience, How was your experience with Sonos in your project? Did you end up using your original plan? Thanks for sharing.