Testing out the Noise Control settings on Sonos Ace on Android/Pixel 7 and noticed with Noise Cancelling or Aware Mode the audio is high quality and full as expected, but switching Noise Control to Off drops the audio quality. It sounds like it changes to mono or at least the treble and bass drop out and soundstage is narrowed. Is this a known issue? Cannot find any other threads about it.
Both the Ace headset and app are updated to latest version today.
Just a suspicion… do you wear glasses?
I need them for reading and for me nearly every over ear headphones are difficult to use when wearing my glasses. It’s not a problem of comfort but they do not fit that 100% accurately than without glasses and that results in a small loss of bass.
I was surprised (because my other over ears don‘t have nc option) that active nc on Ace obviously compensates that.
Without wearing my glasses I notice no difference between nc on or off.
So maybe for you there’s also something that doesn’t allow Ace to fit optimized on your ears?
It's more an issue of switching between Noise Control options in the app and hearing a different sound profile. Noise Cancelling and Transparency sounded normal with a wide soundstage, but selecting Off here narrowed the soundstage and it was more like being on a conference call with Bluetooth headphones where the headset and mic are set to the same device. Low quality output.
Ok.. as said for me (without the glasses) there wasn’t such a remarkable difference in sound quality when switching nc options on or off. Imo it could also depend on the sound file how much difference you hear. But of course there shouldn’t be too much difference. Did you realize the issue on bt music mode or tv swap audio?
The other thing I can imagine is a relation between noise cancellation and 3D / head tracking options. Maybe in tv swap mode active 3D option sounds different with nc turned on or off. I will have to test that myself.
The same imo could be with head tracking option combined with nc or not (which is also available in bt music mode).
Think l‘m going to start some testing sessions. 
I'll do some more testing on the Sonos app, on an iPhone, other audio sources etc to see if it happens there too or if it is an isolated instance of this issue.
Ok, but exactly with the settings you used I would have expected no such difference in audio.
Finally got round to testing again.
iPhone app - all works fine, audio quality sounds the same on Noise Cancelling/Aware/Off modes.
Android app - I cannot change settings in Sonos app now, even with Sonos Ace connected to phone via Bluetooth, still show greyed out and “Not Connected” in the app. Tried forgetting the device and re-adding, same outcome.
I also had this issue and sadly at the moment it seems there could be a conflict if Ace ist bonded with the app on both os, Android and iOS. Using Ace on two iOS / iPadOS decices is no problem, just using the Android app also seems to be ok, but if I use both with Ace, after a while Ace is greyed out on Android app and just a reset can solve that.
I hope the next firmware update for Ace will fix it.
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.