Apple Music doesn’t enable ‘casting off’ for direct play on Sonos in the way it evidently does with Apple’s own speakers. It’s left to the reader to surmise their motives. 

But on the other hand, most recent Sonos products do Airplay, so some mixed signals there about working with Sonos. I don’t myself like Airplay from my experience with it before I installed Sonos, and while stability may have improved, I don't want my phone to needed for allowing its use all the time that music is playing - but that is a different matter.

So: I use a Mac bought in 2014 for the still slick UI, Android phones because iPhone pricing is ridiculous, and Spotify for music service. Horses for courses.

Not really. Whilst the original incarnations of AirPlay were Apple-only (though some reverse-engineered the protocol) Apple has since licensed the AirPlay protocol stack to those wanting to build compatible products. The implementation is therefore in Sonos’ court.

On the other hand integration of a service, especially casting direct to Sonos players, would require work on the service’s side.

Yes, but Apple still has to take the step of giving Sonos the license and thereby green light the implementation. 

On the other hand, casting from Apple Music does not work with Echo either. So it isn't just a Sonos thing from Apple. 

Corporate motives related to cost/benefit are rarely easy to discern. Often, they don't have any motive other than inertia.

PS: Spotify, as a service, casts to both Echo and Sonos. Amazon, who also sells speaker hardware, casts to Echo, obviously, but also to Sonos! 

Can anyone explain then what’s being played when I select Apple Music as a source from within the Sonos app?

See this support article that relates to the current Apple Service in the Sonos App:

https://support.sonos.com/s/article/3282

Erm...ignorance is bliss? As is a glass of wine...to render all music the better.

And I am pretty sure that few, if any other, in the household you referred to, are fussed about this. As they justifiably would be if the UI changed and/or made it harder for them to access the music.

But that’s irrelevant as nobody else uses Music as I do.

256 AAC - and they’re not even embarrassed to say so lol.

Nothing to be embarrassed about - see the link where the head of Apple Music says that the difference between lossless and 256AAC can’t be heard in a blind test by him, and by other Apple engineers. And why they introduced it as an offering for no extra price.

https://djmag.com/news/apple-music-head-says-he-can-t-tell-difference-lossless-audio

As to those rare exceptional 1% to 2% golden ears he refers to, in the interview he also said that even these ears will need very very high quality stereo equipment to pick up the difference. But I can’t see even that happening in a typical domestic room, even a quiet one, because the ambient noise floor is too high to allow that very small difference to be heard. High quality headphones perhaps, where these room noises are completely missing.

Yes I’ve seen you quote this article quite s few times - Cue is like 60 years plus lol.

Joking aside, switching between AAC and Lossless / Hires I can definitely hear a difference on my Arcam / Linn equipment, in my listening room settled in to listen and focus on the music - which is how I listen to music most of the time. Using a Sonos Amp  in that mix may ruin this but I want the option.

Why offer it at all then and incur the associated bandwidth and server resource it entails if they think it’s pointless - it’s not like Apple to follow the crowd. In any case, everyone else has it they should just enable it comprehensively and stop this fence sitting nonsense.

I am 60 plus too, and it is good to now be able to give up pursuing bit rates and just listen to the music instead. Back in the day when I had large Harbeth speakers, I still could not hear the difference between Apple lossless and lossy on them even late in the night, running them from Quad two box amplification fed by an unnecessarily expensive DAC. Level matching was not an issue because unlike what Apple seems to do that makes their lossless streams sound better, sound levels from both options were identical, when fed by a Connect to the same DAC, because both options were sourced by the Connect via NAS. Lossy music was bought and downloaded from iTunes, while lossless was ripped from CDs, as well as CDs themselves playing on a SACD player that housed the DAC.

This was all part of fairly long testing I did before I switched from legacy HiFi kit to Sonos, after being convinced that Sonos did not come with a sound quality compromise in exchange for its much better feature set.

Cue is just another data point that reinforces my belief, albeit a very credible one, even if he may be, as you say, 60 plus.

Another data point for others that may come across this thread:

https://markellisreviews.com/apple-music-lossless-sounds-better-because-its-louder-a-follow-up/

There are two places where I differ with what he says, the first is a minor point - where he says lossless from Apple is slightly louder and punchier. It ought instead to be: louder, hence punchier. And I was to flick the switch as he says between the two streams, and if the lossless stream is louder as he says it is, I know that it will sound punchier to me as well. But I could make the lossy stream to be just so too, by nudging the volume slider to the right.

The notable difference I have is where he says that he does not think that Apple lossless is as good as that from Qobuz as an example. If both services are using the same master for any given album, I can’t see why this should be the case; there certainly is no technical reason for this that I know of. Note though that I have never tested this is a listening session, but regular Spotify and Apple Music on Sonos, I have tested, many times - no difference.

The other thing to think about is the number of people that have threads here wanting the bits to be displayed to be sure they are listening to lossless. Or even Hi Res. Because they don’t get this information from their ears, it would seem.

I have a similar but slightly different issue with the Android S2 app and Amazon Music Unlimited. I was playing Keys to Imagination from one of my favorite albums - Yanni live at the Acropolis, and comparing between casting directly from Amazon Music app and via Sonos app to an Amp + Arc group.

The Sonos app produced a sound where the dynamic range seemed to have been reduced. Aka I was losing out on some of the treble and low bass and the midrange was louder - volume slider unchanged. For example, the Cymbals and drums were much more clearer when directly casting from Amazon app. Same album, same UHD track. I checked the equalizer settings on the Amazon app and it was disabled/flat. It is not something esoteric or funky hand-waving to say one sounds better quality than the other. The effects were very clear.

Till that time I was happily using the S2 app and listening to Amazon music. I just installed and tried the Amazon app directly out of idle curiosity and then it was a moment of surprise. Oh there is that Cymbal sound is it! I am wondering if it is due to some DSP happening inside the Amazon app despite the flat EQ. If it is then I’d say it is good DSP!

Bonjour 

j’ai besoin de réponse svp

Voila je viens d’acheter 2 enceinte play3 au magasin lors de mon achat le vendeur m’a expliqué que je pouvais diffuser la musique qui était dans mon téléphone, mais je m’aperçois que cela est impossible. J’ai des musique que j’ai acheté via Apple Music mais je n’ai plus d’abonnement car j’ai mes musiques je possède un iPhone 11 et ils disent que c’est possible mais je ne trouve pas. Mes enceintes n’ont pas de Bluetooth et quand je vais dans le centre de contrôle et que j’appuie sur AirPlay rien. Comment puis-je faire pour écoutez musique qui est dans mon téléphone est-ce possible ? Y a t’il une application à télécharger car à entendre le vendeur c’était tout simple et j’ai bien expliqué que je voulais écouter la musique qui est stocké dans mon téléphone merci à vous et au plaisir de vous lire 

 @Lydie73 

Sonos discontinued that speaker 3.5 years ago. It doesn’t support Airplay.

Take the Play.3s back to the store and demand a refund. They were ancient stock, and were mis-sold.

If you wish you could exchange them for two Ones which (a) support Airplay and (b) sound better.