Go to Settings —> System —> Port —> Audio Delay and select 75ms.

Check the latency on your DAC and if it isn’t tiny in comparison to the Sonos 75 ms delay a faster one might be an improvement.

I have done this in two places and it works very well, once the delay is set to minimum as suggested, with no lip sync issues at all. Both using the Connect/Connect amp analog line in, but I doubt a Port will be different. I am surprised to read that interposing a DAC to use the digital outs of the TV will by itself add noticeable delay, but do not have much direct experience of that solution.

I have used the stereo audio out jacks on an older LCD TV, wired to line in on Connect and this also allows the TV sound to be piped to other Sonos zones when needed. Except that for stable play, that needed all the Sonos units to be ethernet wired to the base router. But no lip sync issues of any kind.

On a latter day model TV in the bedroom. that lacks the audio out jacks, I had wired the headphone jack of the TV - fortunately, that is there - to a Connect Amp, and that too worked fine. I have replaced that now with powered speakers because I do not need a Sonos zone there, but the Connect Amp worked with no synch issues as well. One advantage of the headphone jack is that because it is volume level controlled, only the Firestick remote is needed to change sound levels of the TV obtained from the external speaker pair.

As an aside - a couple of decades ago I discovered that all my TV sound needs were met by a pair of HIFi quality external speaker pair and if I wanted surround for the rare movie, the multiplex was a better way to get it. I have had no reason to change that thinking till now, and I doubt now that I ever will.

I think people are wired differently as to noticing lip sync problems. I would definitely notice 75ms delay.

It depends on the TV service. Some are inherently awful at sync. UK ones are generally good, especially the major broadcasters. 75ms would be noticeable for speech; not so much for live music, where the Meridians could be of obvious benefit.

Yes, I also notice. When lip sync totally out of your control, eg someone else's TV etc, or a live broadcast interview from sports event etc, there is a possible solution, and works for me:

Don’t look at the lips, concentrate on the eyes.

In my area the movie channels tend to have the best sync. I recently encountered a cable box with horrible sync. Fortunately, adding about 150ms of audio delay helped.

I refuse to accept that I am wired differently; or if so, everyone that has watched my set up is as well. Not one has noticed anything off, be it for movies or for music videos with close ups of strumming/drumming.

Obviously, I am not complaining or interested in investigating this outcome.

Per OP first post, he too has not said anything of suffering any such effect in his old house.

It seems like it could be the TV as well, really anything in the chain from source to sink.  15 ms positive or negative won’t be noticed alone, but they will add up.

I’m sure that you and I are wired differently and I’m not claiming that either of us is ‘standard’. I can be rather brutal in a “my dog is better than your dog” HiFi showdown because, in my opinion, all of the dogs might have fleas.

The goal is to learn what is “best” for you and go with it. Don’t be too concerned if your idea of “best” clashes with another. Hopefully, you don’t live with that person.

Processing delays in the TV signal pipeline shouldn’t matter, as it ought to have audio and video in sync at the point of final delivery. Some will also compensate for Bluetooth latency. It’s where the audio and video streams diverge outside the control of the TV that problems can arise. 

As a general statement, I agree; we would not be human if that was not the case.

But this is not a wiring case in my opinion, because noticing a difference in seeing when a guitar string is plucked and when the note is heard is the same for all healthy humans. As is established by the fact that it is not just I that does not pick out the delay in this case, but no other family member or guest has till now, even when asked if they do so. To repeat what I said.

And casually saying, as 106rallye has, that wiring is different dismisses considering the possibility that there may be something happening in the TV that is compensating for the Sonos delay. I cannot establish that in the bedroom set up because the headphone jack of the TV that is used cuts out the sound to the TV speakers. But the next time I use the other set up in a balcony, I will see if I can hear any sound echo when the TV sound that is set to zero there, is dialled up. Because I do hear an echo if an Echo device wired direct to an amp is played along side one wired to a Connect and thence to another amp or to other Sonos speakers. Again, those differently wired will still hear that echo, I believe.

Both TVs happen to be Panasonic of 2011 and 2019 vintage.

https://www.city.ac.uk/news-and-events/news/2017/04/are-sight-and-sound-out-of-sync

They team found that there was an average auditory lag of 91ms for the phoneme identification task (based on the famous McGurk effect) and 113ms for word identification, but this varied widely between individuals.

Going back to OP original question, would one of these work? Assuming the 75ms delay was acceptable:

http://www.cypeurope.com/store/store/app/product/AU-1HARC/HDMI-to-Stereo-Audio-2-Phono-ARC-extractor

That will work if the TV has the HDMI ARC socket - not all do. But before trying any other hardware, OP should make sure that he has done what buzz has suggested early on about setting the Port for a minimum delay and see the outcome with the DAC hardware he has in place.

Once he does that, OP set up should be equivalent to what he says worked fine with a Connect at his earlier residence, with no visibly intrusive sync delay referred to for that use case. From what I know of DACs, just interposing one between the digital out and the Port analog inputs should not add any delay; Sonos adds the delay because it is needed to get other Sonos units to sync perfectly when grouped, not because its DAC causes it, per se.

I will probably do my testing of my balcony set up tomorrow, to see if the absence of the lip sync issue is accompanied by a sound echo issue when the TV speakers come on; the source for the TV is a Firestick.

I can’t say that I’ve looked in to it that closely, but it seems logical that a device in the pipeline could get away with being out of sync by 15ms or so without it being viewed as a flaw, as no one notice any sync issues with the device specifally.  In theory, several devices in a chain could compound to cause a noticable issue.

Well I know for a fact that my Sony OLED takes quite … a ... while to process the video. Sync with audio direct from an Apple TV was absolutely hopeless. However audio from the TV itself is of course perfectly in sync with the picture, and that includes its own Bluetooth to headphones. 

That would suggest that if a HomePod is used for the TV sound, as it can be if the latest version of Apple TV is the source, wired for video to the TV and wirelessly to the HomePod, the sound would play ahead of the video? With an echo caused if the TV speakers are then turned up?

I have a suspicion that in my Panasonic LCD, the TV  stereo audio out jacks are putting out sound ahead of that from the TV video/audio, and when those jacks are fed into the Connect, the 75 ms Sonos delay is matching the Panasonic delay to the extent needed for lip-sync to look fine.

If I hear no echo when the TV speakers are turned up in my test, it would mean that this Panasonic delay is very close to 75 ms because it takes less timing differences for echos to be heard than for lip sync issues to be intrusive.

The audio direct from the Apple TV was ahead of the picture. But, like I said, audio and video at the TV’s own outputs should always be in sync (subject to any manual intervention via its settings). A TV can’t second-guess what it’s unaware of, downstream of those outputs. 

Result of the test: when the TV sound is turned up, there is a noticeable and therefore intrusive echo when compared to the sound via Connect fed by the audio out jacks of the TV. 

So, I watched separately for lip sync issues with just the TV sound on, and then just the Connect supplied sound on.  Very carefully, toggling between the two more than once. There was, no surprise, perfect lip sync when just the TV sound was playing. But, as in the past, even careful watching left me unable to find a difference I could see between the lips and the sound.

My conclusion: there is something happening in the TV and its speakers that is causing a delay in the sound as compared to what is being put out by the audio out jacks of the TV. But that delay is not 75 milliseconds but somewhere close enough to that such that the lip sync is not affected. But not as close as is required for there to be no echo, which suggests the elimination of echo effect needs a much higher level of temporal synchronisation of video and audio, compared to what it takes for lip sync issues to disappear.

All I can say is that I am happy for what the TV is doing, because it is making the Connect supplied sound to be close enough to the video it is putting out for there to be no lip sync issues.

Back now to an evening of music videos in the balcony, with video from the Firestick into an HDMI input on the TV and audio via the audio out jacks of the TV to Connect to Yamaha stereo amp that has a speaker pair wired to its speaker terminals, a Yamaha Sub wired to one line out on the amp, and a third speaker wired to the second line out on the amp to get sound good coverage for the entire balcony, all with no visible lip sync issues or any echo! I see no further need for looking this gift horse in the mouth, and all will be well as long as the present Panasonic lives because there is no knowing what will happen if the TV is changed.

Ah, well. Music videos are notorious for poor lip-sync (some of which could of course simply be due to miming). 

Test material was Happy Valley on BBC player. All the owts were in good sync!

Update  - my son is so pleased with his HomePod mini pair once it settled down to work flawlessly for music, he decided to replace his Panasonic TV’s Firestick with Apple TV 4K. No issues at all in getting that going, and the user experience is far better than that from Firesticks. And the sound of Apple TV piped direct to the HomePod pair, is in perfect sync with the TV video. So no issues of the kind quoted above which shows that what is happening inside the TV is also influencing final outcomes. And what is happening inside the TV is not consistent across different kinds/makes of TVs.

The sound from just the HomePod mini pair is a big improvement on that from the TV speakers. No atmos - that needs the big HomePod, but that apart I am very impressed with the result. The main TV room set up with a HiFi speaker pair is much better of course, but the trade off for the much smaller form factor of the Minis is surprisingly small, in a small bedroom. And for those that are in the Apple ecosystem, the integration between the phone, the speakers and Apple TV/Siri is very slick. If the TV video syncs well, this is clearly the way to go for those that are invested in the Apple world, with the full size Home Pods for those that must have Atmos.

There’s evidently a trick available to iPhone users to sync the audio and video where the source is Apple TV and the audio is rendered by HomePods. Presumably the iPhone ‘watches’ the screen while it ‘hears’ the HomePods.

Tongue in cheek, or serious?!

I don’t know enough where this tech stands today, to know the answer to that question!

Serious. I was interested in syncing audio/video using an Apple TV 4K to some AirPods but (a) the feature doesn’t work with AirPods, only speakers that can be ‘heard’, and (b) I don’t have an iPhone (but could perhaps have borrowed one). Since the Apple TV’s audio -- via BT to AirPods -- was so wildly out of sync with the new Sony’s picture I gave up and mothballed the ATV.