Port digital output lacking treble

What is the source of your music?

Deezer-->sonos port→ Audiolab Dac-->Naim amp
I have contacted the support.
The root cause is a recent update of the system, Sonos teams are working to solve the problem.
The workaround is to use the RCA outputs.

Wait and see.

Thanks for the follow-up.

Literally, a few minutes ago a PORT firmware update was released. While there is no claim that it addresses this issue, it’s worth checking this out.

my current version is the 

15.2 (nb 72239316) 

And there is no update available…..

I have the same problem with my Port in a simular setting. No treble, sounds dull, after the last update 2 days ago. I use a NAS. It must be an issue with the last update.

The sound signature on the analog output also, again - again, has changed with this update, and when you adjust the balance control via System, the bass and treble also still changes completely randomly.

I'm getting a little tired of never knowing how my Port sounds after an update.

Same issue here, both on my Schiit Modius and ADI-2 DAC FS components. My ADI detects and warns me that the “Pre-Emphasis Flag” is detected on the SPDIF signal coming form the Port. Pre-emphasis means the highs have been boosted to mitigate potential signal noise, and requires “de-emphasizing” for proper playback. 

However, the signal from the Port’s SPDIF out is not actually pre-emphasized, so your DAC detects the flag in the signal, kicks in its de-emphasis support, and attenuates the high frequencies (~2–15KHz) leaving you with a muddy sound. Who knows what the code is actually doing, but this is how it manifests in my systems.

Glad to hear they’re working on a fix, but between SPDIF not working at all on some systems (fixed via recent firmware update), and now this, I’m pretty disappointed. 

I’m disappointed too.

No news from Sonos Support since they asked me if “I have an Audio Precision test device, or equipment that can generate Channel Status Bit metadata over SPDIF” 10 days ago…. 

Testing the 15.3 revision. It’s better. 👍
 

But still on the analog output, when you adjust the slider on fx the balance control, the bass slider still changes completely randomly.