In Ceiling Speakers Placement Advice

I don’t know of any surround sound system, Sonos or otherwise, that uses the speakers in the TV.  Your choices for fronts from Sonos are using a soundbar, or an Amp with two passive speakers, with or without a Sub.  In order to use ceiling speakers for rear surrounds, you would require an Amp in addition to whatever you decide to use for fronts.

Thank you jgatie. So TV and Sonos speakers tied into the a Sonos AMP would work? If so where would you place the in ceiling speakers to get the best sound?

Two Sonos Amps with speakers at the front, bookshelf, in-wall or ceiling (in that order) and ceiling ones behind d the seating positions. A Sonos or other powered sub could be added to the front Amp.

Surround speakers should be behind and to the left/right of the main listening position. 

Thanks Stanley. Could you elaborate on why you suggest two AMPs? 

Just to be perfectly clear….

To use Sonos in your desired setup you will need two Sonos Amps.

• Amp 1 to drive the front speakers of your choice
• Amp 2 to drive the in-ceiling speakers of your choice as surrounds

Topology

• The in-celing speakers should be placed over the seating area to the left and right and approximately one (1) foot to the rear if possible.
• The speakers up front should flank the TV left/right. They will create what's known as a “Phantom” center channel.
• If a sub is used it should be bonded to Amp 1

This overall setup will support 2.0 stereo up to  DD5.1 sound from a source that supports it. It will not support Dolby Atmos.

The surrounds can be set to play in surround mode (Ambient) and FULL stereo for music

As above, an Amp provides two channels of amplified sound, also used as the front channels a line out to a passive sub, or a Sonos wireless link to Sonos a Sub. The surround /rear Amp does not offer the sub options.

So as simple as possible:

Front Amp  - ARC / HDMI in, two amplified channels, sub options and a link to a second Amp for rear channels.

Rear Amp, two amplified channels and a link to the front Amp.

I urge you to retkink this plan, an Arc Ultra (many mounting options) up front and a set of Era-300s for surrounds will provide a far superior listening environment. Even swapping the 300s for an Amp and ceiling speakers would be a big upgrade in sound.

Thanks Stanley - I was shying away from the sound bar because of the aesthetic of it. Is there a functional mounting option that you would suggest to be less noticeable?

A bracket mount that hangs it off the bottom of the TV.

https://www.crutchfield.com/p_051SATM1B/Sanus-WSSATM1-B2.html

I have a different Sanus mount and it is rock solid and good looking.

I’m having difficulty understanding what you mean by “less noticeable”?

1. Below on the left is an illustration using left and right speakers (as you didn’t want in wall speakers). You’ll have an HMDI cable running from the Amp to the TV; as well as speaker wires running across the floor. Also, the power cord to power the Amp.
2. On the right is an illustration of a soundbar. You’ll have one cable (HDMI) connecting it to your TV and a power cord to power the soundbar.

Please advise as to which you think would be less noticeable. 

Understand that using in-wall speakers the grills can be professionally painted to match your wall. I say professionally painted so as not to clog the grill holes as most consumers including I might do. 😂 

With the mount I suggested the Arc's cables are run along the mount and pretty much invisible.

I’ve installed many speaker systems in living-room and tuned in-ceiling arrays for tight spaces. I have always focused on even coverage, clear center imaging, and controlled bass to ensure movie-style impact without heavy room work or awkward speaker sightlines.

For a 20×20 room, place the front in-ceiling pair about 2.5–4 ft from the front wall and centered left/right so the stereo image stays focused at the TV. Put the rear pair just behind the main listening position and slightly wider than the fronts to widen the surround field. Keep both pairs symmetric to avoid tonal shifts. Use a single sub in a corner for strong LF output, then run a quick “sub crawl” to find the sweet spot and set phase. Wire each speaker with CL2/CL3-rated cable, 16–18 AWG, and terminate at a central plate or patch panel for future reconfiguration. Avoid HVAC vents and lighting, fit tile bridges or sealed backboxes where needed, and set the AVR crossover near 80 Hz. Use the receiver’s room calibration, then fine-tune levels while listening to the sound.

Try a free ceiling-speaker layout calculator to draft placements and export a scaled plan. You can also use a Rack diagram tool so you've zero hassles when installing the speakers.