I love(d) Sonos, and have been a customer since 2006. Over time, I accumulated 7 devices over 5 zones (lost a few in the S2 transition, but at least got upgrade prices to port (forgive the pun) over to the new software, which was perfectly reasonable given the developments of the products. It used to be the pride of my living room, and I loved the original independent controller hardware - which gave Sonos a very unique signature and feel, way ahead of its time. Honestly in the last years after the original S2 transition, the whole system has been unstable. I live in an apartment not a house, and wifi is not a concern anywhere (if I can stream 4k video in the “zones” via wifi, that's a decent test) - and yet the system is best described as temperamental. When it worked it was a thing of beauty, but now I can't trust it. The software remains buggy, zones appear and disappear, adding or removing group playback doesn't really go to plan, and the new interface is the least intuitive for some basic things like choosing which zone to make active etc. I can't show this off anymore, and worst still I can't enjoy the system since ive lost faith in its ability to work robustly. The new headphones and the software update debacle explain the delta between the values of Sonos then and Sonos now. Why design new noise cancelling Sonos headphones that are just another bluetooth variant - may as well remove the SONOS brand logo and substitute for another? It only works with Sonos Arc to swap audio, is that really the killer feature? Sonos had good IP and a well fortified eco-system, that people admired and that worked well, they were the apple of audio. They need to get back to their roots, fast. I have ditched the Sonos controller software, and paid up for ROON that interacts with Sonos devices, it's missing the ability to use Spotify but brings the joy of stability and enjoying music back to the forefront, and works flawlessly. It was an expensive way to backdoor into a proper experience  of a networked music system. 

As MrWhoseTheBoss has said on YouTube, they had one job to do. They have a unique USP in being able to make headphones another speaker in the Sonos ecosystem when at home on wifi, with Bluetooth for outside use.

But chose instead to create standard Bluetooth headphones that can also toggle between the Arc. 

I do wonder whether (aside from battery life on wifi) a reason they couldn’t make the headphones part of the ecosystem was because you cannot guarantee someone else in the family/group wouldn’t whack up the volume while you’re wearing them. There’s only a tiny chance it would happen, but it could, and I imagine Sonos needed to have some health safeguards, and this is a big hole. I may be way off kilter here though!

That’s an interesting point that I’ve not seen mentioned before. Since they do connect to Arc by wifi and would appear in the app (I think), can anyone in the house control the volume with the app? 

Not sure. You’re right, if it appears in the app anyway while connected to the Arc, that does open up the same risks. So maybe the volume can only be adjusted by the ‘controller’ that activated the swap from Arc to headphones? In which case, that’s the safeguard right there… Hmm. Told you I could be off kilter. 

First thing I would do is set the device volume limiter in the app if it’s available for the Ace

I just received my Sonos Arc headphones today and feel cheated that they cannot be added to a group or used as any other sonos speaker.  I agree with the comments, these are simply over priced bluetooth headphones.  Shame on Sonos!  I am in mind to send them back and ask for a refund!

That sinking feeling in the pit of your stomach when the most obvious and expected feature is missing from a premium product.

Experiencing that now. It can’t possibly be that Sonos headphones don’t play well with the latest players they offer exclusive of the Home Theatre use case?

That's an upcoming release right folks??

We buy Sonos because of the ecosystem. Ignoring that key point in introducing Ace is an amazing Marketing blunder. 
 

non starter for me as a standalone Bluetooth headphone. 

I totally agree with the negative comments about the Ace headphones. My expectation was that they would be connected as any other SONOS speaker I have, and be able to be grouped.

I am very happy to have waited to here all the reviews before wasting my money on a set of headphones that would not accomplish the main goal I would have for their use. I expected to be able to wear the headphones while watching a TV program and adjust my volume separate from the volume being played on my SONOS Playbar. For all of you disappointed SONOS users who are also looking for a way to allow multiple TV viewers to have separate volume control, here is my solution:

Buy one or maybe a pair of “Sennheiser RS 175 TV Listening System” ($279 retail). I first purchased one of these headphone sets about 5 years ago and they work great. There is no latency issues and the sound is great. I also then purchase another set of Sennheiser RS 175 TV Listening System just recently so that my wife and I may both be able to listen at what ever level of sound without disturbing anyone else in our open floorplan condo. My only reason for wanting the SONOS Ace headphones was because I expected to be able to take them into any room in my condo and group them with the audio on the TV (I have SONOS Playbar on more than one TV).