The AMP connects to an HDMI-ARC port, which is different to a straightforward HDMI port. So perhaps check that your device has the audio return channel. You can purchase an “HDMI-ARC to Optical Adapter” from Sonos.com, if you prefer to go down that route instead.

The Amp, when setup as the front HT device will provide the two HT front channels and a phantom Center channel and it can be bonded with a Sonos sub (or 3rd party active sub) and two Sonos 'matching’ speakers as it’s two rear channels for a 5.1 HT system. 

The rear speakers can be …

• 2 x Play:5 (gen 2) 
• 2 x Play:1 or 3
• 2 x Sonos One (gen 1 or/and 2, or/and SL)*

*Note: The Sonos Ones’s and SL speaker’s can also be 'mixed and matched'.

It is also possible to use another Amp (wireless or wired) or the older Connect:Amp (wired only) for the two rear surrounds but note that all the ports (except speaker connections) on the Amp/C:A become disabled in these circumstances, including the line-in/out and sub.

Hi

@Ken_Griffiths gave some excellent advice. However, it’s been my experience that very few (if any) projectors have HDMI-ARC (CEC) port(s). Even the Epson 5050UB 4K Pro-UHD projector that retails for over $2,500-USD lacks an HDMI-Arc port (click the link).

https://epson.com/For-Home/Projectors/Home-Cinema/Home-Cinema-5050UB-4K-PRO-UHD-Projector-with-Advanced-3-Chip-Design-and-HDR10/p/V11H930020#

Below is my recommendation to integrate a Sonos Amp with a projector of any type using a HDMI/Optical Extractor similar to the one in the link at the bottom of this post:

1. Video/Audio source HDMI-Out to HDMI-In port of the HDMI/Optical Extractor
2. HDMI-Out from HDMI/Optical Extractor to HDMI-In of Projector
3. Optical Out from HDMI/Optical Extractor to HDMI-In of Sonos Amp *
4. Sonos One SL x 2 as surrounds bonded to Sonos Amp (or other Sonos speakers mentioned by @Ken_Griffiths)
5. Sonos Sub bonded to Sonos Amp
6. Two extra HDMI-In ports are available for other devices on the HDMI/Optical Extractor  

* Requires HDMI/Optical adapter shown here

https://www.amazon.com/Optical-Toslink-Extractor-Splitter-Support/dp/B07K5FYW5M/ref=sr_1_12_sspa?crid=2C4LW8GSV095N&keywords=hdmi+optical+audio+extractor&qid=1582120850&sprefix=hdmi+optical%2Caps%2C170&sr=8-12-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExM1FFUU9ORDFFUUJSJmVuY3J5cHRlZElkPUEwODg1NzI4OUY3QzQyTlU2S1IwJmVuY3J5cHRlZEFkSWQ9QTA3ODI5MDYxN1dVSzc5VFQ3TEtIJndpZGdldE5hbWU9c3BfbXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

One minor correction, Ken. It’s an optical to HDMI-ARC adapter, not an HDMI-ARC to optical adapter. 

i have a benq 585 connecting it with line in or hdmi i have delay problems ??

serravalc,

Yes, there will 'most likely' be a noticeable lip-sync delay if choosing to use a line-in connection, plus that will only provide you with a stereo audio signal, rather than surround sound.

However using the HDMI extractor/splitter, as suggested, should reduce delay to around 30ms approx. and that will likely appear to provide you with A/V lip-sync that’s not noticeable… but these things can depend on a variety of external factors. The HDMI/splitter/extractor route will also provides you with a Dolby Digital 5.1 Surround audio signal too from the A/V source, or stereo output. 

Ok?

AMANKA HDMI Audio Estrattore 4K x 2K HDMI a HDMI + Optical SPDIF con 3.5 mm Stereo Audio HDMI Estrattore | Convertitore da HDMI SPDIF Splitter per PS3 PS4 Blu-ray DVD Xbox TV PC
 

https://www.amazon.it/dp/B07C92XMMF/ref=cm_sw_r_cp_api_i_HUuvEbXK11PG2

Does that extractor/splitter you linked to here, have an HDMI-ARC port?? I’m not sure it does? ...

This one does however, that I just found on Amazon UK, but I have not tested this (obviously) nor know how it might perform. So it’s just for your information only .…

.https://www.amazon.com/Audio-Extractor-Splitter-Optical-TOSLINK/dp/B07HR6YK2X/ref=sr_1_20