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A record company is offering free downloads of high-definition music. I downloaded several music files encoded at 24 bit, 192 kHz ALAC. To my surprise, iTunes 12.0.1.26 on 10.10.1 Yosemite imported the track and played it successfully! And it lists that high-resolution information in the file information.

I had thought that iTunes could not play high definition files. I understood it to be limited to 16 bit, 44.1 kHz files. And so I had thought that special software is required to play anything higher than that.

So my question is: When iTunes is playing such files, is it actually playing them at full resolution, or is it down-converting them? (Or whatever the technical term would be for storing or playing the files at something less than full resolution.) I can't tell by ear because I don't have my computer hooked up to good speakers.

  • I don't have any reason to believe that it can't...It should play anything that QuickTime is capable of playing, but I'm having trouble finding any official documentation. I'm going to keep investigating. – Chris A Dec 4 '14 at 23:09
  • The reason I'd thought it can't is articles like this—the opening of a 2014 article in Sterephile by Jon Iverson: “To use the Mac mini for audio, however, I needed a music program. I had no plans to use iTunes—my prior experience with it was not a happy one. Besides, I require high resolution and multichannel playback, and despite iTunes' convenience, Apple tightly controls its file-format repertoire.” He doesn't outright say it can't, but I was sure left with that impression! (stereophile.com/content/music-round-69-page-2) – ChristopherE Dec 4 '14 at 23:18
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    He's probably right in saying that iTunes isn't really appropriate for professional "high-resolution and multi-channel playback". But I think it should be able to manage two-channel, 24-bit, 192kHz at least, with some caveats -- see my answer. – Chris A Dec 4 '14 at 23:25
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    iTunes [or even quick look] has no trouble playing ALAC, or even WAV or AIF files, & has been the case for many years [Mac Pro 08 here]. My system is also limited to 96k/24-bit, even through its external DACs, but it can downsample on the fly for my standard o/p format which is 48k 32-bit float without a glitch. It doesn't like flac or ogg [or wma, but who does like that], which need a converter, but seems happy with just about anything else. (&, btw, you really will struggle to hear the difference; v high rez like that is actually more so that nothing gets lost through the record/mix process – Tetsujin Dec 5 '14 at 8:16
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iTunes uses the same technologies as QuickTime for playback.

According to this document circa 2005, QuickTime is capable of playing 24-bit , 192kHz audio files. I think it's safe to say that iTunes is fully capable of playing these files.

However, you're probably limited by the hardware in your Mac. If you open the "Audio MIDI Setup" app, you'll probably find that your Mac is limited to audio output at 96kHz.

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So, if you want to listen to these files in full 192kHz, you'll need to use a dedicated external USB DAC, and bypass your Mac's internal audio hardware. Please correct me if I'm wrong.

Further reading: http://www.head-fi.org/t/671361/how-to-get-24-bit-192khz-files-from-my-macbook-pro-to-play-through-the-dac-of-the-fiio-e17

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I have imported 96/24 AIFF files (downloads from HD Tracks) into iTunes. I play them on my iMac and MBPro (digital optical out from headphone jack to my PreAmp which has a DAC, and recently I switched over to USB just to see if there was a difference). To my knowledge, as long as you have the correct setting in MIDI (change the sample rate and bit rate to the maximum settings of the DAC). iTunes will play HiRes files. However, recently I loaded Audirvana Plus and am playing my iTunes files through Audirvana and there is a difference in sound. That makes me wonder if iTunes was playing the HiRes files in full HiRes properly. Admittedly, Audirvana bypasses a lot of Apple audio circuitry to reduce noise and this may be the explanation. But nevertheless, I am left believing that iTunes doesn't do HiRes music properly. BTW if you are spending all that money on HiRes downloads, just spend the money on Audirvana Plus (or JRiver) and enjoy HiRes music with greater sound quality than iTunes.

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