Just as video standards have gone from SD to HD to 4K, audio has also been improving the quality on offer. Now high-res audio is the order of the day for those who want the very best listening experience while on the move.
iPhones don't arrive with this as an immediate option, but with an app or two, and some expensive new headphones, you can make it a reality. We show you how to listen to high-res audio on iPhone. For more tips on high-res audio, see How to get high-quality music and audio on your iPhone.
What is high-res audio?
If you listen to songs you've purchased from iTunes, chances are you're not hearing the full sonic landscape as the artist intended.
There are good reasons for this. In order to make tracks with manageable file sizes, they are usually compressed (made smaller) by removing various data that is deemed superfluous. That's why you can fit so many on your iPhone.
For a lot of people this is fine and the songs sound good enough. But if you want richer tunes then you'll need versions that retain all the information.
Essentially there are two types of compression employed with digital music: lossy and lossless. The former is found in MP3 and AAC formats, which also happen to be the most common ones used today. As the name lossy suggests, these are the ones that discard data from the track to save space.
Lossless files include FLAC, ALAC (or Apple Lossless), and DSD. All of which boast CD quality sound or better, and come with enormous files sizes.
Apple offers a selection of music on the iTunes store called 'Mastered for iTunes', which is a step up from standard MP3 or AAC as it involves remastering the tracks to avoid some of the pitfalls that accompany digital compression techniques. But even here there is some lossy compression involved, so it remains something of a compromise.
Another important aspect of the quality of a track is the sample rate. This determines how many times a second the original source material is captured, and the amount of dynamic range.
On a CD the values of these two will be a sample rate of 44.1kHz with a bit rate of 16-bit. High-res audio offers substantially more with 96kHz and 24-bit, so there is increased detail to work with on those tracks.
Where to find high-res audio files
High-res versions are often more expensive than the standard iTunes alternatives. When we were preparing this article, Radiohead's remastered OK Computer OKNOTOK 2017 album was available for £11.99 as a Mastered for iTunes edition, or £18 for a high-res audio version on HDTracks.
Just remember that you'll need to download any high-res files on your PC or Mac rather than the iPhone itself.
You can also set up iTunes so that it imports higher-quality versions of the tracks of any CDs you might buy.
To do this, launch iTunes and go to iTunes > Preferences > General, then select Import Settings and in the Import Using dropdown menu, choose Apple Lossless Encoder. See also: 15 iTunes tips & tricks
Another option is to sign up to the Tidal music service, which offers a high-res streaming option for £19.99 per month.
How to play high-res audio files on your iPhone
Buying high-res audio tracks is one thing. Playing them is another. iTunes and the Apple Music app don't support FLAC or DSD files, so you won't be able use them without re-encoding the files in the Apple Lossless (or ALAC) format or downloading a compatible app.
Importing to iTunes
If you've bought and downloaded FLAC or DSD files from one of the sites listed above, or indeed any other you find, you'll need to import them into iTunes before the Apple Music app can see them.
But, as iTunes doesn't like FLAC files, they'll need to be converted first.
You can find a number of converters online or in the App Store. FLACTunes FLAC Converter, for instance, has very positive reviews and is a snip at £3.99.
Download the app of your choosing, then it will be a case of simply adding the tracks you want to convert and then setting the output format as Apple Lossless or ALAC.
When this is done, go to iTunes on your PC/Mac and click File > Add to Library.
A Finder window will appear, so navigate to your high-res files, select them and click on Open.
The tracks will then be entered into your library, so the next time you sync your iPhone or if you use iTunes Matching you'll be able to access them on your device.
Using a third-party app
If you don't want to go through the whole converting process, and don't mind using an app other than Apple Music, then there is an easy way to get the high-res files on your iPhone.
VLC for Mobile is a free app that's always an excellent choice. It might not be fancy, but it gets the job done.
If you want something with a bit more polish, and don't mind spending £7.99 to access the high-res audio features, then the Onkyo HF Player is the one to choose.
Before you begin moving files, make sure that the music you want is downloaded to your PC/Mac. Now, open the desktop version of iTunes, and plug the iPhone into your computer.
Click on the little iPhone icon that appears at the top of the page and you'll be presented with the general summary screen for your device.
Select Apps from the menu pane on the left side of the page, then scroll the right pane down until you see the File Sharing section.
Under here there should be the music app that you downloaded. Click on it and then in the Documents section just to the right, click on the Add button.
From the finder window that appears, select your high-res audio tracks and click Add.
Now click Sync to move them onto your iPhone, and when this is completed click Done.
To listen to your tracks all you need to do is open the app and the files will be there.
Will my headphones work with high-res audio?
Here's the rub.
The apps will play the tracks, you'll hear them in your headphones, but they won't be any different to normal standard tracks due to the fact that the iPhone doesn't output high-res audio through the 3.5mm headphone jack.
The Lightning port is capable of supporting this feature, but at the moment the only real way to get high-res audio from your phone is to use headphones that have a built in high-res DAC.
Sorry we can't give you a way round this roadblock, but if high-res music is your desire then the chance to buy some new headphones could be a good thing.