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    The Computer Audiophile

    Apple Music's Lossless and Hi-Res Mess

     


    This morning I've been testing Apple Music's new lossless and Hi-Res offerings on both my iPhone 12 Pro running iOS 14.6 and my Mac Mini (M1) running macOS 11.4. In my tests, I'm only concerned with playing the music bit perfectly, in other words without making any changes to the audio. If Apple Music says it's streaming lossless audio, then I want to stream that audio losslessly, rather than accidentally converting it to lossy AAC or MP3 etc... Whether or not people can hear the difference is a topic for another discussion. I'm just making sure I can play the music in its original form and that Apple is sending true lossless and Hi-Res to my audio devices. 

     


    Let's Dig in


    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, in this case from Apple Music, into the playback device hasn't been altered. The source is what has been delivered to Apple by the record labels. Apple is just the delivery company.

     

    If you care about high quality, getting the lossless streaming you're paying for from Apple Music, Qobuz, Tidal, Amazon Music, etc... 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. 

     


    Testing Methodology 

     

    Device 1
    My Apple iPhone 12 Pro running iOS 14.6 and the Apple Music app. I connected the newest version of the Apple Camera Connection Kit to the iPhone, so I could attach a USB Audi interface, and feed power to the phone and interface. 

     

    Device 2
    Apple Mac Mini (M1) running macOS 11.4, and Apple Pro Display XDR, and USB audio interface connected to the ports on the back of the display. 

     
    I use the following testing methodology to test Apple Music. 

     

    The USB audio interface is a Berkeley Audio Design Alpha USB that accepts USB input and outputs audio over AES/EBU or S/PDIF (BNC). 
     
    I use a Berkeley Audio Design Alpha DAC Reference Series 3 that identifies and decodes HDCD on all sample rates from 44.1 up through 192 kHz. When an unaltered HDCD music track is played, the HDCD indicator on the DAC is illuminated. The HDCD flag is on the 16th bit for lossless 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 on my DAC. Apple Music's lossless audio that I tested was 16 bit / 44.1 kHa and the Hi-Res audio was both 24 bit / 176.4 kHz and 24 bit / 192 kHz. 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. Pearl Jam's Live On Two Legs was only released as an HDCD master for its lossless CD version. 
     
    I set a baseline by playing my own local copy of the albums and make sure the HDCD indicator illuminates. I played some Reference Recordings albums through Apple Music on macOS and made sure the app could handle bit perfect playback. All was good there. On iOS, I used used other apps such as Qobuz, to play the identical music through the identical hardware. All was good through the Qobuz app. Again, there are no alternative versions of these lossless albums. It's the same music on all the services that offer lossless streaming.
     
    Absolutely there are possible holes in my methodology, but I believe I've minimized them as much as possible. If anyone can identify a hole, please let me know and I will retest. 
     

     

    Test Results
     
    On macOS, I found no way to play bit perfect lossless or Hi-Res audio from Apple Music. In addition to a couple other nonsensical issues that I'll get into later, Apple is doing something to the music it streams. 

     

    Test 1, streaming Pearl Jam's Live On Two Legs release I was able to illuminate the HDCD indicator for the first couple seconds of playback. After this, the light went out for good, even if I skipped to the next track. When I clicked the play button to start the entire album over again, the HDCD indicator illuminated again for a few seconds. If I had to guess, I'd say this is because of watermarking mandated by the major record labels. Apple has a perfect copy of the album on its servers, the perfect copy starts, but then something changes in the stream that causes the music to not be bit perfect. I'm open to all input on what this could possibly be, but watermarking is my best educated guess for now. 

     

    Test 2, streaming the Reference Recording's album Exactly Like This from Doug MacLeod, displays different behavior and bolsters my aforementioned watermarking theory. This album, from a very small independent record label that I don't believe watermarks it's music, alters between bit perfect and not bit perfect. Upon playback, the HDCD indicator is on sometimes then off for a period of time, then back on etc... I really don't have a good guess for why this happens. I originally thought maybe an adaptive bit rate issue caused it, but even after downloading the tracks to my device offline and playing them, the problem remained. 

     

    Test 3, streaming the Reference Recording's album Break The Chain from Doug MacLeod produced the identical behavior. The only difference here was that the album was Apple's Hi-Res offering at 24 bit 176.4 kHz. Again, no solid bit perfect playback. Something is happening to the music. 

     

    A note about Apple's Hi-Res offerings that makes this a real mess. On Macs running macOS / OS X, the Apple Music app looks at the sample rate in Audio Midi upon the app's launch. Whatever same rate is set there, is the sample rate that Apple Music will use for playback as long as the app is open. OK, fine you say, Apple Music lossless is probably 16 bit / 44.1 kHz and that can be set in Audio Midi. Sure, now for the mess. Apple Music Hi-Res is be definition not 16 bit / 44.1 kHz. It go up through 24 bit / 192 kHz. OK, you can run through the whole dance closing Apple Music, manually setting the sampan rate in Audio Midi, then reopening Apple Music and off you go. Oh no you can't. Apple Music doesn't tell you what the sample rate of its Hi-Res music albums. Thus, you have no idea at what sample rate to set Audio Midi. 
     

    UPDATE: To find the sample rate of the album and play it correctly you have to play a track, click the info button to reveal the sample rate, change Audio MIDI to correct sample rate, restart Apple Music, play the track again. 

     

    How did I find the same rate? Fortunately, the Apple Music app on iOS has auto sample rate switching, which enabled me to get the rate, then sixth back to my Mac to run the tests. This was good because I could see the bit perfect audio stream for the first few seconds once I had the correct sample rate set. 


    Note: the Qobuz app plays this music bit perfect on my Mac.

     

     

    On iOS, as I just mentioned, we have the high benefit of automatic sample rate switching when playing music in Apple Music. The results for Test 1, 2, and 3 were identical on iOS as they were on macOS. Bit perfect for the first few seconds of major label albums. Bit perfect on and off for Reference recordings' albums. Apple Music on iOS switched between outputting 44.1 to outputting 176.4 without an issue. If only the audio would remain bit perfect during playback, it would be a great solution. 

     

    I will note that the Qobuz iOS app played everything bit perfect, but there needs to be an asterisk. For some reason Qobuz resamples the 176.4 Doug MacLeod album Break The Chain at 192 kHz on iOS rather than 176.4. I checked Neil Young's greatest hits to make sure I cold stream 192 material bit perfectly from Qobuz and succeeded. iOS and iPhones are fully capable of bit perfect audio at 176.4 kHz, so I'm not sure why Qobuz is resampling the RR releases. 

     


    What About mQa?

     

    There is interesting news on this front. Some labels have snuck mQa material into Apple Music just like they have on other services. Users of Apple Music can search for mQa and they'll see some albums such as the Radka Toneff Fairytales album. The albums playback as mQa on a DAC in my system that is a full mQa decoder. 

     

    I checked a number of other albums that have appeared on Tidal as mQa only and didn't find mQa for these releases on Apple Music. 

     

    As readers of Audiophile Style know, I'm no fan of mQa and am very pleased it hasn't made its way into more releases or officially into Apple Music. Those who may be reading this as fans of Apple Music, rather than typical audiophile offerings, and aren't familiar with mQa, can get the gist of it and the company from the following videos.


    Part 1 - https://youtu.be/pRjsu9-Vznc
    Part 2 - https://youtu.be/NHkqWZ9jzA0

     


    Wrap Up

     

    As it stands now, Apple Music's lossless and Hi-Res offerings are a bit of a soup sandwich. You can't really stream the audio without some type of DSP going on that makes the music different from the lossless version on CD and on other lossless services. My guess is digital watermarking. In addition, it's not possible to get a consistent lossless or Hi-Res stream for other music that I tested, such as that from Reference Recordings. When I ran into similar issues with Amazon Music HD, using its apps just like I used the Apple Music apps, I was happy to find the Amazon Music HD streams lossless and Hi-Res through third party devices from Bluesound. Given that Apple doesn't integrate with Bluesound, I can't test this. Apple does integrate with Sonos, but as I found previously (link), the new Sonos Port can't stream bit perfect either, so a test on that platform would be useless. 

     

    I will happily update this article if there are holes in my tests or something else changes. As it stands now, I don't know of any holes and I stand by these conclusions. 

     

     

     




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    My previous purchases (before the Apple Music lossless) show:

     

    kind: Purchased AAC audio file

    cloud status: Uploaded

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    Sorry if this has already been asked and answered, but I'm curious and would appreciate knowing whether or to what extent Apple Music is lossless if played via the ITunes App in Windows 10? 

     

    I have been streaming ITunes in Windows 10 through JRiver MC's WDM driver to my DAC via WASPI in ITunes
    using the Windows Audio Session setting (Edit/Preferences/Playback/Play Audio Using Windows Audio Setting). I set the sample rate to 192 kHz and the bit depth to 24-bit in the ITunes App (Edit/Preferences/Playback/Sample Rate For Audio, Bits Per Sample For Audio).

     

    A related question is whether or to what extent Apple Music is lossless if played through a browser via music.apple.com, and whether or not it is better, worse or the same as via the ITunes Windows App.

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    28 minutes ago, The Computer Audiophile said:

    I did a ton of testing today. Will have an updated article Thursday. 

     

    Really interested to read what you have been testing, Chris.

     

    I'm particularly concerned about the AirPlay 2 issue. I had assumed that if I downloaded lossless files to my phone, I could then stream them over AirPlay losslessly, but I keep reading that maybe they are getting converted to AAC by the app before they are streamed?

     

    Have you compared streaming music directly from the Apple servers vs. streaming local files downloaded to an iPhone or a Mac?

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    1 hour ago, Mayfair said:

    Sorry if this has already been asked and answered, but I'm curious and would appreciate knowing whether or to what extent Apple Music is lossless if played via the ITunes App in Windows 10? 

     

    I have been streaming ITunes in Windows 10 through JRiver MC's WDM driver to my DAC via WASPI in ITunes
    using the Windows Audio Session setting (Edit/Preferences/Playback/Play Audio Using Windows Audio Setting). I set the sample rate to 192 kHz and the bit depth to 24-bit in the ITunes App (Edit/Preferences/Playback/Sample Rate For Audio, Bits Per Sample For Audio).

     

    A related question is whether or to what extent Apple Music is lossless if played through a browser via music.apple.com, and whether or not it is better, worse or the same as via the ITunes Windows App.

     

    I don't think the Windows app has been upgraded to support lossless yet? So you are probably just upsampling an AAC stream. I don't think the Apple Music browser player supports lossless, either.

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    3 minutes ago, new_media said:

     

    Really interested to read what you have been testing, Chris.

     

    I'm particularly concerned about the AirPlay 2 issue. I had assumed that if I downloaded lossless files to my phone, I could then stream them over AirPlay losslessly, but I keep reading that maybe they are getting converted to AAC by the app before they are streamed?

     

    Have you compared streaming music directly from the Apple servers vs. streaming local files downloaded to an iPhone or a Mac?

    Yes :~)

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    10 minutes ago, new_media said:

     

    I don't think the Windows app has been upgraded to support lossless yet? So you are probably just upsampling an AAC stream. I don't think the Apple Music browser player supports lossless, either.

    Thanks for the speedy response!  I hope they will upgrade the iTunes Windows app and the browser app to support lossless. But I’m  not holding my breath. 

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    3 hours ago, new_media said:

    I'm particularly concerned about the AirPlay 2 issue. I had assumed that if I downloaded lossless files to my phone, I could then stream them over AirPlay losslessly, but I keep reading that maybe they are getting converted to AAC by the app before they are streamed?


    I suspect the deliberate choice to use 256kbps instead of lossless delivery is a feature, not a bug, to enhance buffering for multi room playback, especially considering many consumers have really poor WiFi networks.  If the company standpoint is that lossless superiority is not audible to the 98% majority, any means to reduce support calls about audio breaking up is advantageous.  That actually makes perfect logical sense if one assumes quality degradation is inaudible, improved functionality becomes the primary factor that deserves optimization (by decreasing bitrate).

     

    In WWDC 2017 it was presented that AirPlay2 enhanced buffering allows you to take out the trash (leave the WiFi network) without music being interrupted.  At 256kbps I calculate this to allow for several minutes.  With lossless compression, this duration may roughly become one third only, which would not be sufficient for taking out the trash.  Audiophiles may ask why would they would want to take out the trash when they are enjoying the music, if you need to ask this question, this feature is not meant for you.  :)

     

    Again I stress that this is my speculation only.

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    Well, I think that I have finally come up with a solution that is (for sure) a fully lossless playback chain, but definitely not bit perfect.

     

    I posted a few pages back that when I stream from an iPhone to an Apple TV 4K, the Apple TV shows that it is playing either lossless or hi-res. I attached the Apple TV to an HDMI splitter with a digital display that gives you information on the audio and video streams, and the Apple TV consistently puts out 24/48 over HDMI.

     

    Using an AmazonBasics HDMI Audio Extractor, I can output the audio over SPDIF. I haven't been able to find tech specs on the audio extractor, but if it can handle 4K video, I assume it can handle 2-channel 24/48 audio.

     

    Right now I have SPDIF into a Sonos Amp via the Sonos optical to HDMI Arc adapter. For as kludgy a solution as this is, it sounds pretty good, and I can use the Apple TV 4K headless.

     

    So, everything is getting resampled to 24/48 and I am running HDMI to optical SPDIF to HDMI Arc, but I think I finally confidently have a lossless playback chain.

     

    Thanks, Apple, for making everything so clear and simple. 🙄

     

     

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    My question to myself (which I am sharing with everyone else) is can I tell the difference between Amazon lossless (non bit perfect) FLAC and AIFF CD's which I ripped to my NAS and play through Audrivana in WASAPI exclusive mode which must be bit perfect?

     

    To make the comparison to my ears equal- I did not play amazon FLAC direct from my network but rather downloaded the FLAC files to my NAS which has a linear power supply.  Ripped CD's are also played from my NAS.

     

    Now I have an extremely revealing system with a Mutec Ref 10 se-120 clock attached to my DDC, DAC, SOTM usb-tx ultra, and two etherregens.  I have a superb linear power supplies throughout my system as well.  I even have a topaz balanced  isolation transformer on my entire system which reduced noise by -165.  Point being- this is about the best it gets- so I should be able to detect differences as well as anyone out there.

     

    Bottom line, FLAC played from amazon in "semi exclusive mode" and AIFF from Audrivana in WASAPI exclusive mode when comparing the exact same songs from the exact same CD's sounds very very close to EXACTLY the SAME.  Perhaps the AIFF is ever so slightly fuller and the FLAC is ever so slightly more dynamic sounding, but the difference is very very very slight.  The music is nearly indistinguishable.  I would have enormous difficulty knowing which option was playing if I did a blind test.  Streaming FLAC on amazon direct from the network and not from my NAS does sound one step below the ripped CD's AIFF files from Audrivana, but it is only fair that if the AIFF is downloaded to my NAS, that the FLAC also be downloaded to the NAS for equal comparison; and to my ears- it is 99% the same.......

     

    I know this bit perfect stuff is big in our world- but my ears cannot tell the difference on a very high quality system.

     

    By the way, on my Audio-gd R-7HE DAC, I have the option for NOS or up-sampling.  To my ears and to the ears of so so many people who report their findings with this world class DAC, up-sample is preferable.  Yet up sample certainly ruins bit-perfect playback; that is non arguable.  Many more technically minded people say all DACs in their processing ruin bit-perfect playback even if it is bit perfect when leaving the computer even in NOS.  

     

    SO- it is fun to talk about this bit perfect stuff- and from a purist viewpoint- I prefer it, but my ears really cannot tell the difference.

     

    Therefore, for me, the biggest deciding factor between all the streaming services is which has the best library for my musical tastes.  $10, or $20 a month isn't making a difference to me.  Spotify and Apple are the best at suggesting the type of music I like- and that is worth something to me as well.  I am not crazy about the Amazon interface either.  But sound quality, amazon FLAC and AIFF from Audrivana are nearly indistinguishable.

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    Hi Chris, really appreciate your work on this. I haven't seen other attempts to actually validate AM lossless (yet), and your transparency is stellar.

    I have to say relying on HDCD in the methodology is, to me, a massive, inherent flaw. We know from long-published investigations[1][2] that HDCD is, at best, flaky, unreliable, poorly implemented, not actually 24bit, and ultimately a failed attempt at pushing beyond 16bit with a format that is, shall we say, unsupportive – and probably a good way to collect royalties for Pacific Microsonic and, later, Microsoft. (If there are proper refutations of these articles I linked, I haven't seen them, and would very much appreciate links. Same for any insight on why we have access to purchasable 24bit audio with the HDCD control packet shifted to the 24th bit instead of the 16th – if we do?)

    It's also very generous to assume AM was supplied the same HDCD-flagged masters as Qobuz or any other service/release. I realize, of course, many artists and labels use distributors for streaming and download stores, and distributors typically will only differentiate sources in the case of Apple Digital Masters, otherwise sending the same source files everywhere. The likelihood that Qobuz received properly HDCD-flagged files but AM did not is probably small, but it's there, and nothing short of confirmation from an artist or label source can settle the matter, sadly. That the HDCD lights up at all from AM clearly indicates presence on some level, but cannot be taken at face value, making HDCD's use in these tests even more problematic.

     

    There is only one proper, fully trustable, most-likely-to-be-foolproof methodology for this, and it is null testing. Completely remove HDCD from the equation, buy or find the files likely to be the same lossless/uncompressed source given to AM, digitally record AM's output stream, match timing and peak levels as close as possible between the originals and AM recordings, then flip the phase of one of them and examine the differential left behind. And film the tests! That was an excellent addition to the Airplay tests to help verify what was going on and not just 'take your word for it'.

    Note that I have no skin in the game here: you seem invested in finding the reality of the situation without bias, as shown in the article updating; and I'm no Apple/AM fanboy, though you obviously only have my word to go on for that. I work in audio professionally (production/events) and I'm afraid these tests currently have too many red flags for me to consider them anything more than curious results definitely raising an eyebrow and inviting further testing. (I'm sure a common question will be why I haven't done these myself, and the answer is simply that I'm not running Big Sur in order to maintain stability of my production setup, so I cannot investigate the Music app's output stream until I eventually update. The iOS app is indeed available to me, but I'd have to investigate just how to grab the Music output without converting to analog, since that would skew the null test. Open to suggestions there!)

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    1 hour ago, seasonsinthesky said:

    Hi Chris, really appreciate your work on this. I haven't seen other attempts to actually validate AM lossless (yet), and your transparency is stellar.

    I have to say relying on HDCD in the methodology is, to me, a massive, inherent flaw. We know from long-published investigations[1][2] that HDCD is, at best, flaky, unreliable, poorly implemented, not actually 24bit, and ultimately a failed attempt at pushing beyond 16bit with a format that is, shall we say, unsupportive – and probably a good way to collect royalties for Pacific Microsonic and, later, Microsoft. (If there are proper refutations of these articles I linked, I haven't seen them, and would very much appreciate links. Same for any insight on why we have access to purchasable 24bit audio with the HDCD control packet shifted to the 24th bit instead of the 16th – if we do?)

    It's also very generous to assume AM was supplied the same HDCD-flagged masters as Qobuz or any other service/release. I realize, of course, many artists and labels use distributors for streaming and download stores, and distributors typically will only differentiate sources in the case of Apple Digital Masters, otherwise sending the same source files everywhere. The likelihood that Qobuz received properly HDCD-flagged files but AM did not is probably small, but it's there, and nothing short of confirmation from an artist or label source can settle the matter, sadly. That the HDCD lights up at all from AM clearly indicates presence on some level, but cannot be taken at face value, making HDCD's use in these tests even more problematic.

     

    There is only one proper, fully trustable, most-likely-to-be-foolproof methodology for this, and it is null testing. Completely remove HDCD from the equation, buy or find the files likely to be the same lossless/uncompressed source given to AM, digitally record AM's output stream, match timing and peak levels as close as possible between the originals and AM recordings, then flip the phase of one of them and examine the differential left behind. And film the tests! That was an excellent addition to the Airplay tests to help verify what was going on and not just 'take your word for it'.

    Note that I have no skin in the game here: you seem invested in finding the reality of the situation without bias, as shown in the article updating; and I'm no Apple/AM fanboy, though you obviously only have my word to go on for that. I work in audio professionally (production/events) and I'm afraid these tests currently have too many red flags for me to consider them anything more than curious results definitely raising an eyebrow and inviting further testing. (I'm sure a common question will be why I haven't done these myself, and the answer is simply that I'm not running Big Sur in order to maintain stability of my production setup, so I cannot investigate the Music app's output stream until I eventually update. The iOS app is indeed available to me, but I'd have to investigate just how to grab the Music output without converting to analog, since that would skew the null test. Open to suggestions there!)


    This has been brought up every time I use the HDCD test, but it has yet to be proven faulty. 
     

    If Apple Music plays an album and the HDCD light goes off and on throughout the track, it’s safe to assume this is an HDCD master. Otherwise, the HDCD light would remain off at all times. 
     

    The reality of doing a null test is less accurate actually because you can’t guarantee which master AM has compared to the baseline / control master. 
     

    HDCD is perfect for this because we know the master is HDCD if the light even flickers once. Plus, investigating masters by talking to the owner of the record label, recording engineering who made the recording, and person responsible for delivering it to Apple, is conclusive in my book. 

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    2 hours ago, seasonsinthesky said:

    Hi Chris, really appreciate your work on this. I haven't seen other attempts to actually validate AM lossless (yet), and your transparency is stellar.

    I have to say relying on HDCD in the methodology is, to me, a massive, inherent flaw. We know from long-published investigations[1][2] that HDCD is, at best, flaky, unreliable, poorly implemented, not actually 24bit, and ultimately a failed attempt at pushing beyond 16bit with a format that is, shall we say, unsupportive – and probably a good way to collect royalties for Pacific Microsonic and, later, Microsoft. (If there are proper refutations of these articles I linked, I haven't seen them, and would very much appreciate links. Same for any insight on why we have access to purchasable 24bit audio with the HDCD control packet shifted to the 24th bit instead of the 16th – if we do?)

    It's also very generous to assume AM was supplied the same HDCD-flagged masters as Qobuz or any other service/release. I realize, of course, many artists and labels use distributors for streaming and download stores, and distributors typically will only differentiate sources in the case of Apple Digital Masters, otherwise sending the same source files everywhere. The likelihood that Qobuz received properly HDCD-flagged files but AM did not is probably small, but it's there, and nothing short of confirmation from an artist or label source can settle the matter, sadly. That the HDCD lights up at all from AM clearly indicates presence on some level, but cannot be taken at face value, making HDCD's use in these tests even more problematic.

     

    There is only one proper, fully trustable, most-likely-to-be-foolproof methodology for this, and it is null testing. Completely remove HDCD from the equation, buy or find the files likely to be the same lossless/uncompressed source given to AM, digitally record AM's output stream, match timing and peak levels as close as possible between the originals and AM recordings, then flip the phase of one of them and examine the differential left behind. And film the tests! That was an excellent addition to the Airplay tests to help verify what was going on and not just 'take your word for it'.

    Note that I have no skin in the game here: you seem invested in finding the reality of the situation without bias, as shown in the article updating; and I'm no Apple/AM fanboy, though you obviously only have my word to go on for that. I work in audio professionally (production/events) and I'm afraid these tests currently have too many red flags for me to consider them anything more than curious results definitely raising an eyebrow and inviting further testing. (I'm sure a common question will be why I haven't done these myself, and the answer is simply that I'm not running Big Sur in order to maintain stability of my production setup, so I cannot investigate the Music app's output stream until I eventually update. The iOS app is indeed available to me, but I'd have to investigate just how to grab the Music output without converting to analog, since that would skew the null test. Open to suggestions there!)

    Let’s leave the general discussion about HDCD for another day. 
     

    The test methodology Chris is using is simple and very effective. In fact, the LED lights up and stays on as expected when it appears the stream is bit perfect and does not light on and stay on when it appears the stream is not bit perfect. Chris went above and beyond in using the specific content he did with the approach strengthening the use case. FYI I spoke with R.R. about their 24 bit HDCD content and they told me the flagging is only used for checking bit perfect playback. I’m not certain all HDCD DACs can be used with 24 bit HDCD content, but Alpha DAC appears to support it. 
     

    I don’t agree with your assessment of null testing. It’s great at comparing pristine files. However, capturing the output of hardware means you are capturing the signal and any inherent noise from the playback scheme. Also, keep in mind that the noise changes with time. As such, you can generally forget about a full null when comparing files with playback recordings through a system. 
     

    So if Chris is using HDCD content for testing I’m going to take his word for it. 
     

     

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    @seasonsinthesky 

     

    For what is worth, I made some tests using the null method, recording the stream and comparing it with an original counterpart track.

     

    I could’t test AirPlay 2 because I don’t own an AirPlay 2 device. Actually I own two of them: an Apple TV and a HomePod. They simply aren’t suitable for testing for obvious reasons: Apple TV’s output resamples everyting at 48kHz and with the HomePod is impossible to know what it is receiving and, besides, it doesn’t support Apple Music lossless yet.

     

    My AirPlay 1 tests (iOS/iPad OS -> Mac and Mac -> Mac) confirm what Chris found out. I couldn’t test the system-wide AirPlay 1 on Mac, only within Music app.

     

    My USB loopback test on Mac doesn’t match with Chris’s test. In my case the tracks are nulled.

     

    I even managed to make a loopback USB test with iPad. I haven’t shared it publicly yet because I find it quite convoluted and so prone to variables that could ruin the reliability.

     

    I will share it, in case. Anyway, for the record, even in this case the tracks don’t null.

     

    Basically, with the exception of the USB test on Mac and excluding what I couldn’t do, almost everything matches Chris’s tests.

     

    I find the HDCD test quite interesting and definitely worth to be considered. The null test is theoretically very valid. Unfortunately certain crucial conditions have to be met: the recording has to be “pure”, without any alteration and the original file used for comparison has to be exactly the same file provided by the streaming service. The former is somehow possible to keep under control, the latter … well not really.

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    1 hour ago, Marco Klobas said:

    My USB loopback test on Mac doesn’t match with Chris’s test. In my case the tracks are nulled.

    We should look into this one further. 

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    Hi, I have done a null test on AM with ipad to dac to pc via spdif.

    There is definitely a small amount of noise added to 16bit material and it shows as 24bit on a bit meter.

    I show the evidence in my video 

    anyone can replicate this test you just need a control source like qobuz to verify 16bit on the meter then send the same track on AM

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    7 hours ago, Marco Klobas said:

    My USB loopback test on Mac doesn’t match with Chris’s test. In my case the tracks are nulled.

     

    Album/track, sample rate, bit depth, other settings, etc.  There may also be other factors such as presence of certain apps like BitPerfect, integer mode, etc.

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    15 hours ago, The Computer Audiophile said:

    We should look into this one further. 

     

    8 hours ago, wklie said:

    Album/track, sample rate, bit depth, other settings, etc.  There may also be other factors such as presence of certain apps like BitPerfect, integer mode, etc.

     

    I redid the test.

     

    I'm using the same album over and over again because it's the only album I bought after the introduction of Apple Music. Every previously matched album is unfortunately still provided by Apple's servers in AAC. It's a common issue.

     

    This time, at least, I changed the track. 🙂

     

    I tried to provide as much informations as possible, documenting every step. My obsession with graphic produced a tall image. I divided it in three pieces. I hope they are usable (download it, in case).

     

    Part 1/3:

     

    spacer.png

     

    Part 2/3:

     

    spacer.png

     

    Part 3/3:

     

    spacer.png

     

    I even tried a second "hardware loopback" test:

     

    spacer.png

     

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    😀 I speak for myself: no. At least, not in a relaxed way, as it should be.

     

    I do listen without all these bit perfect/lossless/whatever distracting thoughts between the tests, though.

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    Thanks for the details.

     

    I'm not familiar with these software or how they are normally professionally used, so I'm a bit surprised to see 32-bit float.  I wonder if there is any virtual soundcard driver to capture the 24-bit or 16-bit integer data to make the setup simpler.

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