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    The Computer Audiophile

    The Sonos Port Isn't Bit Perfect

     

    As the title says, the Sonos Port isn't bit perfect. What's the big deal? For many Sonos users this is a non-issue because they are streaming from very lossy services such as Apple Music or Pandora. However, for people who care about sound quality, this is a big deal because the music sent though the Sonos Port has been digitally processed before anyone gets to hear it. Before digging in further, let's take a step back and define some terms and explain some additional details. 

     

    port-front-angle.jpgSonos is mostly known for its speakers, but the company has also always offered a component with built-in digital to analog conversion and a digital audio output. The Sonos Connect was the previous generation of said component, and the Sonos Port is the current version. I have both components in my listening room, connected to the same system for testing. 

     

    These Sonos components with digital outputs have always been terrific for those of use seeking high quality audio because we connect the digital output to the DAC of our choice and send the signal on to our refined audio systems. Many audiophiles I know do this as well as tons of custom installers around the globe have connected these Sonos components to outboard digital to analog converters. The reasons for this are that Sonos has the most content (think the regular services, but also Pandora and SiriusXM) and the products work very well. Connecting the Sonos Port to an outboard DAC can elevate the audio performance to another level because the internal DAC is somewhat limited. 

     

    What is bit perfect and why should I care? In the simplest terms, bit perfect means that the audio hasn't been changed. The music sent into the component is the exact same music that comes out of the component. If you care about high quality, getting the lossless streaming you're paying for from Qobuz, Tidal, Amazon Music, etc... or about playing a local library of ripped CDs without unknown signal processing taking place, then you should care about bit perfect because without it you have no idea what's happening to your audio. If this isn't a concern for you, no worries. 

     

    port-back-angle.jpgThe Sonos Connect and the Sonos Port both have settings that are supposed to enable digital audio to traverse through the units without any digital signal processing. The Connect works as it should and outputs bit perfect audio without an issue. The Port on the other hand, can't output audio without some type of signal processing taking place inside the unit. 

     

    To test this, I setup both the Connect and the Port identically. Both units were set "Fixed" Line-Out Level. Even though the terminology suggests this line out is the analog output, it also effects the digital output, as seen in my testing. Fixing the output level just sets the volume to 100% and prevents the Sonos from reducing bits to reduce the volume of the music. When this is set, the EQ can't be adjusted. I looked through all the other settings and made sure there wasn't enabled anything that could change the sound. Both units were identical.

     

    Keep in mind that the Sonos S1 app is used to configure the Connect and the new Sonos app is used to configure the Port. This shouldn't be an issue because the settings are the same no matter which app sets them and the audio being sent to the units doesn't route through the iOS app or desktop apps. 

     

     

    Sonos Port Issues 01.jpg Sonos Port Issues 02.jpg 

    Sonos Port Issues 03.jpg Sonos Port Issues 04.jpg Sonos Port Issues 05.jpg

     

     

     


    Testing Methodology 

     

    Once the units were setup, I use the following testing methodology to determine that the Port wasn't outputting bit perfect audio. 
     
    I use a Berkeley Audio Design Alpha DAC Reference Series 3 that identifies and decodes HDCD on all sample rates. When an unaltered HDCD file is played, the HDCD indicator on the DAC is illuminated. The HDCD flag is on the 16 bit for CD files and the 24th bit for high resolution files. Any alteration, DSP, volume leveling, etc... changes this least significant bit and won't enable the HDCD indicator to illuminate. Given the Sonos units only support 16 bit / 44.1 kHz audio, I only tested this resolution. That's the hardware piece. 
     
    With respect to source files, here's what I do. 
     
    I have a list of roughly ten known HDCD albums (although I could use more if needed). Many of these albums were only released as HDCD encoded CDs/files. There is no alternate lossless version. For example, Reference Recordings only releases CDs that are HDCD encoded. 
     
    I set a baseline by playing my own local copy of the albums and make sure the HDCD indicator illuminates.
     
    I used the Sonos applications on iOS and macOS for playback during this test. 
     
    Through the Sonos apps and the Sonos Connect, I streamed my known HDCD releases first from my local ripped CD copy, then through Qobuz, then through Tidal, and finally through Amazon Music HD. I wanted to use my local file baseline, then a few streaming service baselines.  

    Then I tested the Sonos Port using the same procedure. Local files followed by streamed versions from the lossless services. 
     
    Absolutely there are possible holes in my methodology, but I believe I've minimized them as much as possible. I also reached out to Sonos in an effort to check my methodology and show them the results, but I didn't receive a response. 

     


    Test Results

     

    Using the Sonos Connect, everything I sent from my locally stored ripped CD and all the streaming services was bit perfect. As long as the Connect was setup correctly, I couldn't get it to fail. Bit perfect every time. 

    Using he Sonos Port, I couldn't get it to pass a bit perfect audio stream no matter what I did. In other words, it failed every test. Local stored ripped CDs and streamed music from all the lossless services were all altered between the time they entered the Sonos Port's ethernet input and the time they extend the Port's coaxial digital output. 

     


    Conclusion

     

    Take this for what it's worth. Some people won't care, while others will want to look for better solutions. I highly recommend the Bluesound Node 2i as a replacement for the Sonos Port. The Bluesound ecosystem doesn't have Pandora or SiriusXM, but for most people it has everything they need and it's bit perfect with local and streamed content in all supported resolutions up through 24/192. 

     

    Perhaps Sonos will explain what digital signal processing is taking place inside the Port or even issue an update that enables users to turn off this DSP and output bit perfect audio. Until such time, the Port is a hard pass for me. 

     

     

    Sonos Port HERO.jpg




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    How large was the sound difference? 

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    On 3/12/2021 at 10:19 AM, The Computer Audiophile said:

    No. 

     

    HDCDs played bit perfectly by any digital output into an HDCD DAC, will light up the HDCD indicator. It's the same for DTS signals. If the component can pass bit perfect signals, the DTS component will see it and indicate it's DTS.

    In fact, I have a bunch of HDCDs that I ripped originally to 16/44 as if it were standard CD (I had no means of decoding HDCD). You can now run ffmpeg to decode those files into 24/44 files. 

     

    Instructions for mac:

     

    Files must be FLAC, not WAV or AIFF. <Album> is the directory where you have your original files. It assumes the ffmpeg binary is in the directory above and assumes that directory also includes an outfiles directory. 

     

    At the command prompt do:

    % cd <Album>  

    % for f in *.flac; do ../ffmpeg -i “$f” -af hdcd “../outfiles/$f"; done

     

    This will transcode all HDCD 16/44 files into 24/44 files. The output will tell you if the files were HDCD encoded or not. Metadata is preserved.

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    does anyone know if the sonos amp is bit perfect?

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    I’ve juste finished to make a few tests as I have both connect and port on board still for a few weeks until the connect will extinguish itself :) 

     

    speaking about processing, there is no doubt that Sonos pass signal through its DSP in variable and fixed mode. By the way, even with the analog output you can hear it on high resolving systems. BUT, when you set the output to Pass Through… then you recover the Fixed output from the old Connect, even better. The DAC is I think better and you can hear it with a good preamp/integrated amplifier and interconnects. Details and sound stages even if they are not as good as high end dac are convincing from my point of view regarding a wam sound signature at the opposite from SABRE Delta-Sigma constructions. Connect was not analytical as well, Port is in the same sound signature, but with better silence and less boomy low end.

     

    I did not test the digital output yet, but as it is stated it will not process anything greater than 24/48. This is Sonos choice since years. 

     

    despite that I like the client, the interface, the easiness to send flow of audio to multiple place in the house. the airplay 2 coupling works perfectly and without any delay from any source (iphone, ipad).

     

    upnp works also smoothly, integrating sonos into an openhome network with bubbleupnp or with room. Sonos can stream external flow, but with a slightly different sound signature depending on the sources I have tested (minim, room, qnap upnp). the internal streaming mechanism seems to be sensitive to this kind of jitter.

     

    This was my 5 cent on this topic, but, please make your tests in pass through mode (see S2 settings) to avoid going through the DSP and try to reverse powerplug because there is a HUGE difference there too (set phase on the upper pin, not the one close to the cable)

     

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    1 hour ago, Musiq said:

    I’ve juste finished to make a few tests as I have both connect and port on board still for a few weeks until the connect will extinguish itself :) 

     

    speaking about processing, there is no doubt that Sonos pass signal through its DSP in variable and fixed mode. By the way, even with the analog output you can hear it on high resolving systems. BUT, when you set the output to Pass Through… then you recover the Fixed output from the old Connect, even better. The DAC is I think better and you can hear it with a good preamp/integrated amplifier and interconnects. Details and sound stages even if they are not as good as high end dac are convincing from my point of view regarding a wam sound signature at the opposite from SABRE Delta-Sigma constructions. Connect was not analytical as well, Port is in the same sound signature, but with better silence and less boomy low end.

     

    I did not test the digital output yet, but as it is stated it will not process anything greater than 24/48. This is Sonos choice since years. 

     

    despite that I like the client, the interface, the easiness to send flow of audio to multiple place in the house. the airplay 2 coupling works perfectly and without any delay from any source (iphone, ipad).

     

    upnp works also smoothly, integrating sonos into an openhome network with bubbleupnp or with room. Sonos can stream external flow, but with a slightly different sound signature depending on the sources I have tested (minim, room, qnap upnp). the internal streaming mechanism seems to be sensitive to this kind of jitter.

     

    This was my 5 cent on this topic, but, please make your tests in pass through mode (see S2 settings) to avoid going through the DSP and try to reverse powerplug because there is a HUGE difference there too (set phase on the upper pin, not the one close to the cable)

     

    I tried every mode available. 

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    So you're saying it downsamples 48K source sampling to 44.1Kz, ok but my concern more importantly is what about 24k bit depth? Is it chopped off at 16?

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    2 minutes ago, The Computer Audiophile said:

    I’ve done the tests. No matter who comments on the Sonos forum about how things should work, I have objective proof they don’t work that way. 

    That other thread from just a month ago  confirms your measurements.

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    Just now, MgP2804 said:

    That other thread from just a month ago  confirms your measurements.

    Ah. I read it quickly and though it was another, “here’s how it works because it just does,,,” type of comment. 
     

    Thanks for the follow up. 

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    Hey, I'm having difficulty understanding some of this information.  Hopefully someone can help clarify, I'm connecting my turnable to an existing Sonos system.  Here is how it's set up:

     

    Turntable > phono preamp > Five (line in),  playing on Five and grouped with other Sonos speakers in other rooms.

     

    Turntable > phono preamp > Port, playing on Sonos speakers in other rooms.

     

    -Will both of these setups yield the exact same result in audio?

    -Will the DAC of the Port be used, even if I'm not using an analog out?

     

    Thank you!

     

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    51 minutes ago, kayoti said:

    Hey, I'm having difficulty understanding some of this information.  Hopefully someone can help clarify, I'm connecting my turnable to an existing Sonos system.  Here is how it's set up:

     

    Turntable > phono preamp > Five (line in),  playing on Five and grouped with other Sonos speakers in other rooms.

     

    Turntable > phono preamp > Port, playing on Sonos speakers in other rooms.

     

    -Will both of these setups yield the exact same result in audio?

    -Will the DAC of the Port be used, even if I'm not using an analog out?

     

    Thank you!

     

    The DAC in the Port is bypassed, but you are using the ADC in the port to convert analog to digital, before it’s sent to the Sonos speakers. 
     

    For the most part, the sound will be the same in both configurations. There is a double conversion happening, from Analog (turntable) to digital (in the Sonos for sending/receiving and digital signal processing / volume control) and back to analog (output from the speaker).

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    Hi - I just came across this discussion. 

     

    In the tests, you "setup both the Connect and the Port identically. Both units were set "Fixed" Line-Out Level."

     

    On my Port, I also have a setting called "Pass-Through" which is in addition to the Variable and Fixed settings. Have you tested the Pass-Through setting to see if it makes a difference?

     

    Thanks

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    35 minutes ago, Parsnip said:

    Hi - I just came across this discussion. 

     

    In the tests, you "setup both the Connect and the Port identically. Both units were set "Fixed" Line-Out Level."

     

    On my Port, I also have a setting called "Pass-Through" which is in addition to the Variable and Fixed settings. Have you tested the Pass-Through setting to see if it makes a difference?

     

    Thanks

    Yeah, I tested that without a difference.

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    Thanks. I wonder what that setting is for then. 

     

    I have a Port and I'm wondering whether to get an external dac. Is it worth it? 

     

    I dunno. 

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    I'm wondering if you still have the Sonos Port and have had the opportunity to retest recently? Sonos works with Apple Music and so many other services so just ticks the boxes for me - bit perfect isn't a deal breaker but would be great to confirm if it is still fiddling with the data.

     

    Thanks

     

    Bevan

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    3 hours ago, Bevok said:

    I'm wondering if you still have the Sonos Port and have had the opportunity to retest recently? Sonos works with Apple Music and so many other services so just ticks the boxes for me - bit perfect isn't a deal breaker but would be great to confirm if it is still fiddling with the data.

     

    Thanks

     

    Bevan

    Not sure if you are asking me, but yes, I still have mine.

     

    I bought a Rega Elexa mk4 amp, which contains an integrated dac, so I am running the Port into that. The Rega dac  does sound a little better that the Port's one.

     

    Personally, my advice would be to go and test your preferred set up or range of set ups in a shop if you can, and if you like the sound of it, make purchase on that rather than a on some theoretical data fiddle. 

     

    If you are happy with the sound, but it. 

     

    But each to their own etc (usual disclaimer).

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