In my experience, decisions to make changes like the ones we've seen are rarely done in the engineering and/or QA labs.  It's far more common for the IT folks to be forced into wholesale changes by marketing and/or management.

So, after my first post above, I have done some more testing on an Arc/Sub (gen 2) and 2x Sonos Ones, trying to isolate the subwoofer issue.  Not saying this will work for everyone, but if, like me, you are a music lover - this *might* work.

I split my system above into two rooms, 1 with just the Arc and another with the sub and both Ones.  As I have all of them in my office Ive never used the multiroom setting/playback before.

Strangely, when I played the music simultaneously in both ‘rooms’, I am getting the ‘old’ performance of the subwoofer back (Ive just turned it down to +2, it made me so happy lol) in conjunction with the Arc and Ones doing what they should.  

My wife even came down and shouted at me for turning the music up (I hadn’t) so this is the ultimate acid test!!!

Will test it more tomorrow evening - strangely, I now cant get Dolby Atmos via Amazon Music whereas I could before (probably because I split the Arc and the rest up, so the 2x ones and sub as a ‘standalone’ wont support it?) but as a music lover I would rather have respectable across the board music performance in ultra HD until a proper fix is deployed.

Hope the above helps anyone in a similar position to me - Ive sent 4 diagnostics to Sonos to hopefully help them in case this is in any way relevant. 

**Further update**

Regarding the above, volume 1 now sounds like 10 post 14.12, volume 10 sounds like 30 ish post 14.12 - cant go any louder than 10 now as I will end up divorced.

Should say this ‘fix’, if it is one, only works for music streaming.  I dont have a TV in my office, and had the Arc connected via optical out to a Creative X4 soundcard, which is linked via USB C to my computer, so I can game in 5.1 (albeit not Atmos, which I knowingly accepted).

Appreciate this will be a minority setup, so if your Arc is plugged into a TV via HDMI splitting the system like this may compromise Atmos/surround for films, and you will also lose the ability to independently control the rear speaker levels as they are not configured as this.

However, if you want to rescue your system purely to stream some music how you want it to sound, this appears to work!!!!!

#14.12 fightback

Sounds perfectly feasible as the Ones are now driving the Sub, not the Arc.

At least they only did a number on the Arc and not all the speakers on S2.

So,
Lets summarize everything:

1. Almost 2 months no information about the fix, also no fix
2. The flagship device is neglected and so are the customers who bought it for thousands...
3. Instead of prioritizing the firmware fix, they are advertizing another product. I call that direct insult to their customers, yeah directly in the face!

Actually, i dont care anymore. The fix may come next week, month or never,  but it will never erase the negative emotions.
I feel very insulted and neglected!

Sonos hasnt been the top-of -the-line system in the market, but their customersupport used to be the main reason I continued investing in their products. First they skipped the support at Twitter and they never show up in the forum. or communicate with us. 

Nowadays, I´m a bit ambivalent, to say the least. Takes a lot to invest in more forthcoming products, nor will I recommend it to anyone.

And the mini is now official!

Now fix 14.14 ffs!

14.15 out no updates for speakers though 

Wtf?

Just what I said

Is there 14.15 out? I am not at home and no realease notes on the website so can't clarify …

If this ain't fixing the problem then my hope for Sonos has went down the drain... 

Just seen it on the release notes :

Added after release:

Added software support for Sonos Sub Mini.

My previous theory was that they messed up the sub 3 sound profile beacuse of the new release of sub mini , pasting the sub mini profile to our regular subs ?

Is It possible or not I don't know ... But that little sub must have something to do with our systems being broken now...

I have decided to replace the arc next year as a birthday /retirement present hopefully I can unload it and get some money back 

Shame I really enjoyed my system until these last couple of updates but it sounds cheap and nasty now I will never buy any other products from them 

Trueplay still not working, same 100hz cheap bass sound. This is a COMPLETE JOKE!

FFS!!!

This is crazy!

The sound is just terrible since 2 month ago.

I've been in contact with the support and asked for a refund because of the terrible new software. They responded that its more then a hundred days since I bought the system, so forged the refund!

Sonos can obviously destroy your system with an update and then just walk away? WTF???

I bought my system because of the amazing power that could lift the roof on my house, and now its like listen to the television speakers!!! 

I am furious that they have announced the sub-mini, but still no communication on the fact they have wrecked the flagship Arc and Sub.. 

Absolute joke customer service… I wont be buying anymore Sonos products

They remove all the negative comments we post on the new sub mini announcement…

Probably going to ban me... I got enough... Even moderators are incompetent and can't answer to us , just remove the comments...

My posts were removed too. I feel like i already have the sub mini since 14.12, so no need to buy it.

14.15 is out but there are no release notes out at this moment. Software only so far, no following hardware updated notice yet.  https://support.sonos.com/s/article/3521?language=en_US

Near as I can tell, the only change in 14.15, released today for S2, is the inclusion of the speaker definitions for the mini-sub, so any sound profile changes are still in process. Hopefully in testing at this point. 

This is beyond ridiculous at this point. 2 months later and still no fix. All Sonos cares about is making more money. New sub mini release but you still can't sort out the problems with the last couple updates. Give us back 14.10. Thanks for ruining my summer. 

On the Apple App Store :

“What’s New” 

Version 14.15 

“Bug fixes and improved performance” 

So far, seems this was an update for the App only as I didn't see the Arc system itself update.