Hi. I am not clear whether you are using the Amp for the front speakers or the rear speakers? If for the rears then what are you using for the front speakers?

The Amp will be wired to the rears in the ceiling which I wish to use as surrounds, then I want to use a couple of Ones wirelessly as LF and RF

Make sense?

No I am afraid not. That would not work at all for surround sound. Your options for the front are another Amp and speakers, a Beam or (soon) an Arc.

From a practical POV, how is the beam (or arc) different to the amp + 2x ones at the front?

Ignoring the centre channel differences....

The Beam/Arc has the necessary HDMI-ARC input to connect to the TV, the 2 x Ones do not.  You cannot use the HDMI-ARC input on the mp when it is used as surrounds.

So you saying the wireless Ones won’t receive the ARC from the TV if the Amp is powering the rears?

It was my understanding that it was the subwoofer port capability that is disabled when the Amp is used as surrounds.

Could then I use instead of the Ones, some other wired passives at the front given the amps connectivity?

You would need a second Sonos Amp to drive passive front speakers and to provide the phantom centre.

There has to be a Sonos HT compatible device at the front, which manages the whole surround sound process and distributes sound to all the channels.

Then there are the usual options for the rears, one option being an Amp and two wired passive speakers. 

Also note that the subwoofer port is for a third party subwoofer. With any of the achievable setups I have described you can use a Sonos Sub.

Ok, if I just had the Amp + wired passives using ARC from the TV, would I still be getting a considerably better sound than from just the TV until I get a beam/arc and fronts?

But your wired speakers would be behind you if you were using the planned ceiling speakers, and there would be no sound from the direction of the TV. It would be terrible.

You don't need 'fronts'. The Beam or Arc does the three front channels. If you want to get greatly improved TV sound, start with an Arc.

Ok that’s good advice, last question:

What if instead of placing the passive ceilings in the rear I place them near the front of the TV (my house it’s still under construction), and then get a pair of Ones on stands in the back corners and keep the Amp outputting stereo?

Is that a practical solution instead of the Arc even if it’s not a “true surround” setup?

It's possible but I don't think I would recommend it. It would be OK for music, but imagine yourself watching the action or dialogue, but the sound is coming from way up above. I think it would be weird.

Tbh I am not a fan of ceiling speakers at the best of times, although they are visually very discreet, but for front speakers in a HT, ...nah.

Like I said it’s not a full on HT, just a TV room with what I hope would be a better sound setup for things like gaming and sports...

Even so, I would not personally want my main TV audio from ceiling speakers. But it's your choice in the end.

The Arc alone may give you all you want, but putting in ceiling speakers while you are building would do no harm

Where would the Amp to drive them be located, if and when you installed it?

Probably inside the TV cabinet becuase I’ve got 3x HDMI ports in the wall which run cabling behind the wall and out again to sit behind the mounted TV at 5ft above ground, so no visible wires.

I had to go ceiling becuase space is a limiting factor, room is 12ft long and 15ft wide....

If your going to use an amp for the front speakers, I would use in wall or bookshelf speakers over ceiling speakers.  It’s going to sound much better, and I’ve tried it both ways.  ceiling might be ok for sports, but will be rather bad for gaming where direction of the audio is rather important.  

Is there a reason you don’t want to go with a soundbar like the Arc?  I get the space is limited, but a soundbars where made to for rooms with limited space.

2 reasons:

1 - I’m after a clean look with little exposed wires and hardware 

2 - It’s a hard argument with the mrs to make any further holes in the wall

The room will be multi-use so TV and music so any other suggestions will be welcomed....