Why not? Wifi is at the speed of light. Quality may not be as good if there is interference or distance, but that is a different matter.

Radio waves travel at the speed of light. But the “Sonos Beams + Sonos One on Wi-fi” solution, as a whole, involves a lot of other things which bring along overhead.

From the top of my mind:

• processing the audio (in a various form of codecs it might be), extracting “rear left / rear right” channels and outputing them to the correct designated rear speaker
• signal encryption/decryption (the OneSL is connected to a wi-fi network, just like the beam bar is, which most likely is encrypted...).

These cost time. Yes, very little amounts of time. The question is if those delays are big enough to affect the surround sound experience or not;  when we’re talking about delay between video and audio, any time interval matters.

So I’m not convinced, that’s why I’m asking people who really had an used such a setup.

All the overhead would equally apply to getting the signal to the speaker units in the beam.

Or, for that matter, that first “time sink” applies equally to wired solutions. 

I’ve used both wired, and now Sonos. I can detect no difference.

To minimize this possible delay front the Beam to the surrounds Sonos utilises a dedicated 5Ghz link between Beam and surrounds. I have a set up that consists of a Beam, two One's (ad a Sub) in the front room and have not noticed any lag from front to back. Not on surround (but the nature of surround - ambient- sound means lag would be less noticable), nor on music (where you would notice lag or sync problems sooner).

106rallye is correct, Sonos uses the low latency 5 GHz band to minimize the delay.  There is a very slight delay (I think I remember it being +28 ms??), but that is below the threshold that would be detectable (-125ms to +45ms - as found by a study conducted by the International Telecommunications Union)  

As to the processing and/or encryption causing a delay, there is no delay for these.  The slight delay is only for buffering purposes to decrease dropouts, just as it is for the analog Line-In.  The 5 GHz just needs a smaller buffer than the 2.4 GHz due to the low latency mentioned above.

Great answers everyone! There is a very minimal, unnoticeable delay. If you do notice a lip sync issue between your Sonos device and the TV, it’s not likely inherent or caused by the wireless, and is likely an issue with the audio not getting to your Beam quick enough, which can happen if the source device is slow. I’ve seen some TVs that prioritize their video processing at the expense of their audio output.