If the Ace only support 16/48 over usb then the iPad would need to downsample to 16/48 otherwise the Ace wouldn’t be able to decode and play the audio.
...
Assuming it isn’t a usb driver issue or Dolby Atmos/Spatial Audio for headphones isn’t enabled then Windows and MacOs should pick up all the supported formats.
Definitely an odd one with inconsistent reporting when plugged in to different devices. In reality if it wasn’t for the hires marketing machine, nobody would be any wiser because there would be nothing showing them any values 
In iOS there is a Dolby Atmos option which can be switched off, but Apple default the option to ‘Automatic’ - so it enables/disables, as required. The Wireless Streaming Audio Quality Settings can be adjusted by the user too in the iOS settings - see the attached screenshots
Within the Amazon Music UHD App the user can simply tap the graphic to switch the streaming audio between Atmos audio and HD/Ultra HD stereo - that’s the image on the iPad screen I posted earlier with the Ace - the left panel is Atmos audio - tapping the right panel switches it to HD/UHD stereo quality audio (and vice versa)… er .. allegedly.
♂️
Hope that makes sense and clarifies things further.
Yeah, from your various screenshots I’m inclined to believe the Amazon App is getting it right.
Personally I think it would be odd for the Ace not to support 24/48 over usb and it feels like it would need extra effort to limit them to 16/48 I can see a plausible reason for Windows & MacOS to only show 16/48 as available.
Where it all falls apart is @HiFi Oasis Sonos contact confirmed 16/48 as the limit.
Sometimes wanting to know how things actually work is a curse and the best thing is to ignore the technical details and just enjoy it. 
Thanks.
however with the 3.5 jack the Sonos Ace have a much lower volume than the USB C counterpart. So from Mac the audio quality is considered to be the bare minimum…
I can think of a couple of reasons why 3.5mm → usb would have a lower volume than usb → usb
mac → 3.5mm cable to usb → ace
In this situation you have 2 independent volume controls. The Mac and the headphones, so if only using the volume control on one device you might not reach max volume.
If both the Mac and Ace are at max volume and it is still lower than you like, then the 3.5mm to usb cable could be impacting the max volume.
The output jack on the Mac has a max power level. Similar to how different impedance headphones can be quieter (assuming same efficiency drivers) the Mac output might not have enough power at max volume to reach a high enough volume level using the 3.5mm cable, so when the ADC converts it back to digital at the usb end it is a lower volume than using a direct usb connection.
Headphone impedance can be a source of frustration on PCs as the power output from the motherboard 3.5mm socket isn’t enough to drive all headphones at volumes people want.
mac → usb → ace
In this situation the ace are the volume control. The Mac keeps out the way and doesn’t alter the volume it just sends the digital signal to the ace for it to decode.
Thanks a lot for explanation.
Andrea
Sometimes wanting to know how things actually work is a curse and the best thing is to ignore the technical details and just enjoy it.
Even if you are not that way inclined, and don’t care how it works, you may subconsciously enjoy it more if it has a nice ‘placebo’ logo displayed or a higher ‘marketing’ number shown etc.
If the Ace only support 16/48 over usb then the iPad would need to downsample to 16/48 otherwise the Ace wouldn’t be able to decode and play the audio.
...
Assuming it isn’t a usb driver issue or Dolby Atmos/Spatial Audio for headphones isn’t enabled then Windows and MacOs should pick up all the supported formats.
Definitely an odd one with inconsistent reporting when plugged in to different devices. In reality if it wasn’t for the hires marketing machine, nobody would be any wiser because there would be nothing showing them any values
In iOS there is a Dolby Atmos option which can be switched off, but Apple default the option to ‘Automatic’ - so it enables/disables, as required. The Wireless Streaming Audio Quality Settings can be adjusted by the user too in the iOS settings - see the attached screenshots
Within the Amazon Music UHD App the user can simply tap the graphic to switch the streaming audio between Atmos audio and HD/Ultra HD stereo - that’s the image on the iPad screen I posted earlier with the Ace - the left panel is Atmos audio - tapping the right panel switches it to HD/UHD stereo quality audio (and vice versa)… er .. allegedly.♂️
Hope that makes sense and clarifies things further.
Yeah, from your various screenshots I’m inclined to believe the Amazon App is getting it right.
Personally I think it would be odd for the Ace not to support 24/48 over usb and it feels like it would need extra effort to limit them to 16/48 I can see a plausible reason for Windows & MacOS to only show 16/48 as available.
Where it all falls apart is @HiFi Oasis Sonos contact confirmed 16/48 as the limit.
Sometimes wanting to know how things actually work is a curse and the best thing is to ignore the technical details and just enjoy it.
I reached out to my contact again and asked to talk to someone from the engineering side, fingers crossed 
Regardless of any of the technical speculation, I think the Ace sounds really good and I’m happy to use them on a regular basis.
Hi, it may be my impression but between IPad Pro m4 I listen via bluetooth and with a USB C cable that in theory the audio should pass loseless I prefer the first option. With Tidal. Tidal via USB gives on the songs that are 24bit 192khz in Bluetooth a sentence comes out that says that the audio will be compressed ... but it does not give the quality …
Andrea
Hi, it may be my impression but between IPad Pro m4 I listen via bluetooth and with a USB C cable that in theory the audio should pass loseless I prefer the first option. With Tidal. Tidal via USB gives on the songs that are 24bit 192khz in Bluetooth a sentence comes out that says that the audio will be compressed ... but it does not give the quality …
Andrea
I expect tidal is showing you the details of the file it is receiving, not what is going out of the usb cable.
With bluetooth, there isn’t any codec that can transmit 24/192 lossless, so if you have “upto 24/192” set in the tidal app for quality, then any bluetooth connection will perform compression of the original source.
Even Apt-X lossless is only 16/44.1 lossless or 24/48 lossy according to Qualcomm, so under ideal conditions with Apt-X lossless over bluetooth, Tidal would still warn about compression unless you set the incoming max to up to CD 16/44.1 at which point it might not.
https://www.qualcomm.com/news/releases/2021/09/qualcomm-adds-bluetooth-lossless-audio-technology-snapdragon-sound
With usb, depending on what is connected, it is possible to send 24/192 with the right device and may need exclusive access to the audio system enabling, or setting the OS default. The Tidal app is unlikely to be performing any changes to the stream and the ipad/mac/pc/whatever will resample as needed for what is supported by the device plugged in.
You need to see what the audio bit size and sample rate is on the headphones or usb output to know what is actually being sent, rather than the source format the app is receiving.
You need to see what the audio bit size and sample rate is on the headphones or usb output to know what is actually being sent, rather than the source format the app is receiving.
where can I see it from?
Thanks.
Andrea.
If they playback app doesn’t show the chain similar to Ken’s Amazon app then I’m not sure. Maybe someone has written an app that will show details of usb audio if Apples sdk allows it.
I rarely play music from my iPad so haven’t needed to know as I just use either airplay or the internal speakers depending where I am at the time.
If Sonos don’t show the details for the headphones in the app, then there is probably little chance of getting the info from the headphones directly.
In general regarding Sonos products, they have generally stayed out of the hires hype. Their main speakers, port and amp support 24/48, but they haven’t chased higher numbers. It’s never really been their thing, so it would be strange for the headphones to suddenly start focusing on numbers.
Sonos is Sonos. Like many brands they have their own sound signature. My Yamaha avr’s and speakers have a different sound to Sonos speakers, port & amp using the same source. Sonos are selling their ecosystem, sound and ease of use (current situation not with standing) they’re not selling end to end purity of bits.
