Already asked on the forums. 

Already asked but cannot ask again to make them to pay an attention on it? Has the issue been fixed? What’s your point by sending me that link? 

Common courtesy suggests you search to see if a question has already been asked and answered before posting. If, on the other hand, you already know the answer, don’t post it as a question. 

The other post includes a response from a Sonos rep, which I thought you’d find helpful. 

The issue is unlikely to be fixed within your return window. 

Sonos seems to claim this was fixed in an update but that is not true..I have updated the Ace but they are still way too loud at minimum setting 

https://en.community.sonos.com/portable%2Dspeakers%2D229130/potential%2Dbug%2Dsonos%2Dace%2Dstarting%2Dvolume%2Da%2Dbit%2Dhigh%2D6896987

I just updated my Ace. It’s still the same. Nothing was changed. It’s still way too loud at minimum setting. So Annoying.

I was able to fix this issue by doing the following on Android:

Enable Developer Options in System Settings

Disable Absolute Volume. This prevents syncing the system volume with the device Bluetooth volume.

Set the system media volume to about 50%.

Adjust volume on the Sonos Ace to comfortable listening level.

I just tried listening to Spotify on an iPhone via Bluetooth and the minimum volume is too loud using the latest firmware. 
 

Seemingly from the passive aggressive responses above the minimum volume has already been lowered but it remains too high. 

I was able to find a solution on Android but I am unsure about iOS. This is the first headset I have used that seems to strictly adhere to the volume/gain for the phone rather than using its own volume scale. I think this is something they can fix if they get enough eyes on it. Sonos is monitoring this other thread so please try to post on there for maximum exposure:

Please fix volume way to loud on lowest setting