This is somewhat challenging, Sonos isn’t designed to be used in this manner.

The ultimate question is, where is the PC outputting sound? My suspicion, based on your image above, is that it should be going out the Digital Audio port (S/PDIF), which means that you would connect an optical cable from that port on your PC (wherever that is) and connect that to the adapter (US link provided, but check your local store) purchased from Sonos that transfers an optical signal to an HDMI-ARC signal. That adapter would then go to the Sonos Amp (not the Sonos CONNECT:AMP, that’s an entirely different issue) but you’d probably want to ensure that the PC is sending a stereo output, or at best a Dolby Digital output. The optical cable is of limited bandwidth. 

Again, this is a pretty non standard use of this system, I make no guaranties of functionality. 

Hi thx for reply 

The S/PDIF is on the motherboard, next the mic, line-in and other audio door.

my Sonos Amp is these: https://www.sonos.com/en-gb/shop/amp?gclid=Cj0KCQiAq5meBhCyARIsAJrtdr43Ky6BXkQ-66od5P8ksGGuDnSnqEvRC5kBz1F0IueIGJMwz9upHCwaAs5xEALw_wcB&gbraid=0AAAAADqeg_fZhE00whqgJg2CxpRRPVaQZ&gbraid=0AAAAADqeg_fZhE00whqgJg2CxpRRPVaQZ&gclsrc=aw.ds

If I go in the app, at line-in setting and select level source 8 (sugest by operator), there is option for select source laptop and pc, so it probably can work, if this operation exists.

sonos and pc are 2mt fare

operator say, normally  the system work if 3.5mm (of RCA to 3.5mm cable) is connect to mic door of pc, but look like not in my case.

do you think, if I buy S/PDIF cable, can solve the problem?

Not sure I understand what 2mt fare means, it’s not an English phrase I comprehend. 

Since you didn’t fill out the information on your account, I can’t tell what your native tongue might be. 

I *think* that if you follow what I said in my first reply, it should work. But ultimately, it depends on the output of your PC, and not Sonos. Again, this is absolutely non-standard stuff. I wouldn’t be doing it, I’d be buying normal PC speakers for my computer, not trying to jury rig some odd connection to Sonos that might perhaps work. 

Sorry for my bad English 

if I remember well, you asked how far the Sonos was from the pc, it's 2 meters away.

I have logitech g560 speakers connected to my pc, but my pc is also the media server of the house. 
I continue to use the recessed ceiling and wall speakers with sonos amp, via streaming services, but I often need to play audio from my pc.

Today I try to connect an S/PDIF cable, if this is not enough, what should I check in the pc to make it work?  enable any port?  install software?  to install a driver or plug-in?

I don’t know, sorry. I’m not familiar with your PC, the hardware or software it has on it, and how they might be working together.

Ah, so 2mt means 2 meters? What is ‘fare’? I’m assuming ‘apart’, which would make sense in context?

If you shared your native language with us, we might benefit from using Google translate. I wouldn’t worry particularly about your English, it’s much better than any version of your own language that I have, and your posts are mostly readable, it’s just when we drift into more esoteric concepts, it becomes more challenging. 

Sorry, I tend to work mostly in the Mac world. You may want to ask for assistance on a PC based forum, rather than here, where people are focussed on Sonos speakers, not the way that PC systems work. I can give you all sorts of suggestions for your Sonos (and have), but while I do use a Win11 system occasionally, it’s not my area of expertise. 

Google Translate: 

Scusa, tendo a lavorare principalmente nel mondo Mac. Potresti voler chiedere assistenza su un forum basato su PC, piuttosto che qui, dove le persone si concentrano sugli altoparlanti Sonos, non sul modo in cui funzionano i sistemi PC. Posso darti tutti i tipi di suggerimenti per il tuo Sonos (e ho), ma anche se occasionalmente utilizzo un sistema Win11, non è la mia area di competenza.

I know you have mac, but do you think you can help me, if I show you this picture?

I connected sonos to the pc via sonos s/pdif adapter, the pc detects that there is audio out, but I hear nothing from the speakers.

One thing jumps out at me since you’re using an optical cable which has limited bandwidth. Turn off DTS audio, it can not travel through an optical connection. 

If that doesn’t help, try reducing the frequency, but as I said, I’m not familiar enough with the PC in order to give you much intelligent guidance there, sorry. You’d likely be better talking with Sonos Support directly, and not me. 

The only other thing I can do is point you to the Sonos FAQ for using a line in. 
 

Google translate:

Una cosa me llama la atención ya que está utilizando un cable óptico que tiene un ancho de banda limitado. Apague el audio DTS, no puede viajar a través de una conexión óptica.

Si eso no ayuda, intente reducir la frecuencia, pero como dije, no estoy lo suficientemente familiarizado con la PC para brindarle una guía inteligente allí, lo siento. Es probable que sea mejor que hables directamente con el soporte de Sonos y no conmigo.

Lo único que puedo hacer es indicarle las preguntas frecuentes de Sonos para usar una línea en.

One more resource for you to look at is:

Thx I see, but all fine from my side.

Do you think if I use these between pc and sono amp, can be helpful? I have 1 in my storage.

FX Audio dac-x6 Hi-Fi Optical/Coaxial/USB Digital Audio Amplifier DAC Decoder - Black https://amzn.eu/d/9mtsiWU

I wouldn’t think so. But it depends on which signal you’re getting from the PC. If you’re using that optical port, it’s already digital, and wouldn’t work to be re-digitized by a DAC. However, if your using the analog output from the PC, such as you might with a headphone outlet, you’d probably want to skip the digitizing as an extra step, and just use the analog RCA jacks on the Amp. The challenge there, especially with a headphone jack, will always be the “level” of the output from the PC, which is variable by the volume setting on the PC’s output. If you went that route, you’d want to set the output on the PC at least to 50% to start, to ensure that enough signal is getting sent to the Sonos. 

Google Translate:
Non lo penserei. Ma dipende dal segnale che ricevi dal PC. Se stai usando quella porta ottica, è già digitale e non funzionerebbe per essere ridigitalizzata da un DAC. Tuttavia, se stai utilizzando l'uscita analogica dal PC, come potresti fare con una presa per le cuffie, probabilmente vorrai saltare la digitalizzazione come passaggio aggiuntivo e utilizzare solo i jack RCA analogici sull'amplificatore. La sfida lì, specialmente con un jack per cuffie, sarà sempre il "livello" dell'uscita dal PC, che è variabile dall'impostazione del volume sull'uscita del PC. Se hai seguito questa strada, vorresti impostare l'uscita sul PC almeno al 50% per iniziare, per assicurarti che venga inviato un segnale sufficiente a Sonos.

thx I will try