In the last few years, high-resolution audio (HRA) has hit the mainstream, thanks to the release of hi-res audio players, streamers and music services.
From dedicated devices like new Sony Walkmans and Astell & Kern players, to games consoles like the PS4, smartphones like the LG G6 and Samsung Galaxy S8, and better-than-CD quality streaming services like Qobuz and Tidal, it seems everyone's getting in on the high-res audio party.
So how does high-res differ from standard digital music formats? Downloads from sites such as Amazon and iTunes, and streaming services such as Spotify, use compressed file formats with relatively low bitrates, such as 256kbps AAC files on Apple Music and 320kbps Ogg Vorbis streams on Spotify.
The use of lossy compression means that data is lost in the encoding process, which means resolution is sacrificed for the sake of convenience and smaller file sizes. With regards to sound quality, then, these formats aren't telling the full story of our favourite songs.
This might be fine when you're listening to music on your phone using cheap earphones on the bus, but serious music fans should want better. This is where high-resolution audio comes into play.
Astell & Kern, LG, Samsung, Sony, FiiO and Pioneer are just some of the companies to have launched hi-res audio compatible products, while several download sites now offer better-than-CD quality music files. HRA also has the support of major record labels and musicians.
But what does high-resolution audio actually mean? Where can you get it? And what do you need to play it on?
What is high-resolution audio?
It’s worth pointing out that the definition of high-resolution audio isn’t set in stone. Unlike high-definition video, which has to meet certain criteria to earn the name, there’s no universal standard for hi-res audio.
But the term tends to refer to audio that has a higher sampling frequency and bit depth than CD - 16-bit/44.1kHz. High-resolution audio files usually use a sampling frequency of 96kHz or 192kHz at 24-bit, but you can also have 88.2kHz and 176.4kHz files too.
Sampling frequency refers to the number of times samples are taken per second when the analogue sound waves are converted into digital. The more bits there are, the more accurately the signal can be measured in the first place, so 16-bit to 24-bit can reveal a noticeable leap in quality.
The Digital Entertainment Group, Consumer Electronics Association and The Recording Academy have, together with record labels, come up with a formal definition for high-resolution audio.
As well as the definition - “Lossless audio that is capable of reproducing the full range of sound from recordings that have been mastered from better than CD quality music sources” - there are four different recording categories based on the source of the file.
There are several high-resolution audio file formats to choose from, all of which support the above sampling rates and bit-depths. They include FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec), both of which are compressed but in a way where (in theory) no information is lost.
Other formats include WAV, AIFF and DSD, the format used for Super Audio CDs. The relative merits of the formats can be argued, but most crucial will be compatibility with your particular products and system.
The Recording Industry Association of America (RIAA) has issued a logo that will show up on every track and album that can be classed as hi-res audio.
FLAC tends to be the most popular format, scoring points over WAV for better meta-data support (that is, ensuring your tracks have artist and title information). They also take up less storage space than WAV files, which is crucial if you want to pack in loads of hi-res albums on your portable player.
Of course, as well as downloading - and now streaming - your music in these superior formats, you can - and should - also rip your existing music library in these higher-quality file formats.
What’s so good about hi-res audio?
Obviously the main claimed benefit of high-resolution audio files is superior sound quality over compressed audio formats.
To illustrate why they should sound better than MP3s, for example, let’s compare the relative bitrates. The highest quality MP3 has a bitrate of 320kbps, whereas a 24-bit/192kHz file is transferred at a rate of 9216kbps. Music CDs are transferred at 1411kbps.
24-bit/96k or 24-bit/192kHz files should therefore more closely replicate the sound quality that the musicians and engineers were working with in the studio.
With more information to play with, high-resolution audio tends to boast greater detail and texture, bringing listeners closer to the original performance.
Where to buy and download hi-res audio?
There are currently a handful of UK download stores and several US and European sites, though not all of them let you purchase from the UK. Here are a few of the best:
Pioneering US high-resolution music store HDTracks is now available in the UK, initially launching with more than 10,000 uncompressed high-resolution albums.
The company says it has partnered with every major record label – including Sony Music Entertainment, Warner and Universal – to create the world's largest catalogue of hi-res audio files.
HDTracks has also announced a deal with Liztic, a music management application that aims to deliver a seamless digital music experience across PC, Mac, Android and iOS.
MORE: HD Tracks review
7Digital lends its catalogue to a few of the other names on this list, but it also runs its own service at the same time. It stocks hi-res audio files for most genres, not just classical and jazz. The website is easy to navigate and downloading your tracks is a piece of cake.
MORE: 7Digital review
Better known for its home entertainment systems, Naim has a nifty sideline in hi-res audio files, including music from its own Naim Label.
Its site offers music in 320kbps MP3s right up to 24-bit/192kHz WAV, FLAC and ALAC files. Hi-res albums cost between £9.99 and £16.99.
MORE: Naim Label review
Linn’s website offers what it calls Studio Master downloads in 24-bit/192kHz FLAC and ALAC, as well as 24-bit/96kHz, 16-bit/44.1kHz and 320kbps MP3 formats. A Studio Master album costs £15, or £12 in CD quality.
MORE: Linn Records review
Bowers & Wilkins Society of Sound
Another hi-fi brand that turned its hand to hi-res downloads, B&W has a site boasting a range of studio-quality albums. You can also subscribe and access albums not available in the store. Files are available in 24-bit and cost £15.
French website Qobuz launched in the UK back in 2014 and offers in excess of 20,000 high-resolution albums. Files are available at a minimum of 16-bit/44.1kHz while many are offered in 24-bit/192kHz. High-resolution files are also available through the Qobuz streaming service.
MORE: Qobuz Sublime review
Building on the return of the brand in the form of new AV products, Technics has also launched a download store, complete with high-resolution music. The store claims ‘tens of thousands’ of tracks are available.
MORE: Technics Tracks review
Onkyo Music uses 7Digital’s catalogue of music, the same used by Technics Tracks, with hi-res audio downloads available as 24-bit FLACs from 44.1kHz to 192kHz. It also has support for MQA files - more on that later.
MORE: Onkyo Music review
This store offers a huge selection of classical music in WAV, FLAC and DSD formats. It offers tracks from the big labels, as well as some smaller ones you might not have heard of.
MORE: Primephonic review
Sony, Warner and Universal have also announced that they will make their extensive music catalogues available to hi-res download services – all of which is a real shot in the arm for fans of high-resolution audio.
With all sites, make sure it’s clear what file format and bitrate you are buying.
Hi-res audio streaming?
Tidal and Meridian demo high-res streaming
The Qobuz and Tidal streaming services now offer hi-res audio files, alongside their better-than-CD-quality files. This puts them a step ahead of streaming rivals Google Play Music, Spotify and Apple Music.
It's also possible to stream hi-res audio on Android, and now Apple smartphones. Of course, you'll need a smartphone that supports the high-resolution audio format, such as the Sony Xperia Z5, Huawei P10 and P10 Plus, LG G6 or Samsung Galaxy S8 and S8 Plus.
The Apple iPhone doesn't natively support high-resolution FLAC files, only ALAC (Apple Lossless Audio Codec). However, if you have FLAC files ready to store on your iPhone, you'll be able to see and stream them with the right software. Onkyo's HF Player App is our go-to choice, thanks to its reliability, although you will need to pay £8 to unlock the HD section. Check out our full guide to playing hi-res music on your iPhone.
High-resolution music does come with a downside: file size. A hi-res file can typically be tens of megabytes in size, and a few tracks can quickly eat up the storage on your device, and be difficult to stream over wi-fi and mobile data. Thankfully, there's a new file format in town, originally developed by Bob Stuart, co-founder of Meridian, called MQA - Master Quality Authenticated.
The purpose of an MQA file is to take a fully fledged hi-res audio track and compress it into a file size similar to MP3. The result is a hi-res track that can be easily streamed over most mobile and home networks.
It's this format that has enabled Tidal Masters, the hi-res audio section of Tidal.
What do I need to play it?
From AV receivers and stereo amps, to all-in-one music systems and streamers, a growing number of products on the market are handling high-resolution audio.
There remains a certain amount of variation when it comes to file handling and maximum bitrate support on different devices, so check the specifications match your requirements before you buy a new product.
Some systems allow you to play hi-res files directly from USB storage devices or from a networked PC via ethernet. And this Sony turntable even lets you rip your tracks from vinyl into hi-res audio files.
More after the break
You can also play high-resolution audio stored on a PC by connecting it to a USB DAC such as the Arcam irDAC (pictured, above), the Naim DAC-V1 or the T+A DAC 8, then feeding the signal on to a power amp, powered speakers or headphones.
You will need a high-resolution audio player, as not all music software is compatible. As we've mentioned, iTunes will play hi-res files but not FLAC files.
You can even buy dedicated headphone amps with built-in DACs that handle hi-res audio. The ever-popular Sonos system supports WAV and AIFF files but only up to uncompressed CD quality. And it seems it won't support hi-res anytime soon.
If you do fancy a wireless multi-room system that is geared up for hi-res, check out the Bluesound family of products.
Hi-res music on mobile
The iPhone 7 sadly doesn't support hi-res audio out of the box, but there are apps (such as Onkyo HF Player) which will allow you to transfer and play a multitude of hi-res file formats. Once you've got an app that can handle hi-res audio files on your iPhone, you will need some additional hardware to get it to play, as the internal DAC doesn't support the format.
Instead, you'll want a pair of Lightning headphones that bypass the iPhone's DAC in favour of their own hi-res capable DAC. Like the Audeze Sine, for example. Alternatively, you can connect an external DAC, such as the Chord Mojo.
Android mobile users can also stream hi-res music on their phones courtesy of Qobuz - Tidal remains at CD-quality on mobile for now.
Best hi-res audio streamers
Best music streamers under £600
Tested at £430 / Now £499 at various retailers
“A wonderfully expressive and detailed sound served up with a brilliant design and extensive feature list”
Tested at £500
“A superstar, improved. Pioneer has done it again.”
Best portable hi-res music players
High-resolution audio doesn't have to be saved for home listening any more. Companies such as Sony and Astell & Kern believe we should be able to access high-resolution audio on the move, and as such, have produced portable hi-res music players. Here are our favourites, in price order. Click through for the full reviews, latest prices and more details.
Tested at £50 / Now £49 on Amazon
A tiny but talented music player.
Tested at £170 / Now £159.99 at Currys
Lots of detail, small size, expandable memory.
Tested at £400 / Now £250 at Amazon
Stylish design with great sound and impressive battery life.
Tested at £500 / Now £499 at various retailers
Another great A&K music player if you're prepared to pay a little more.
Multi-room high-resolution audio
Multi-room audio products have seen a major boost, with many manufacturers looking to expand their product arsenals and new manufacturers looking to steal the limelight from multi-room trail-blazer, Sonos. And with Sonos only streaming at a maximum CD-quality 16-bit/44.1khz, there's scope for stealing a march.
Bluesound entered the market in 2014, promising high-resolution, 24-bit audio across the entire range - and we've been seriously impressed with both its first and second generation products. Products in the range include the Node 2 wireless streamer, Powernode standalone streaming music player, Vault high-resolution music server, Pulse all-in-one music streaming system and Duo 2.1 speaker system and subwoofer.
Other multi-room audio systems have followed the lead of Bluesound, with systems such as the Denon HEOS, LG Music Flow, Lenco PlayLink, Harman Kardon Omni and Monster SoundStage all offering hi-res support on their new wireless speaker systems.
See all our Bluesound reviews
With more support than ever before, hi-res audio is a viable choice for anyone interested in audio quality, whether part of your home audio system or when on the move.
Manufacturers including Bowers & Wilkins, Naim and Linn have been pushing for and producing high-resolution audio products for some time, and we’ve now seen mass-market heavyweights such as LG, Samsung and Sony adopt the format to bring it to a larger audience.
With this wider availability, more people are able to learn and understand exactly what high-resolution audio is, and the benefits it can bring to music. There's plenty of content out there, and there's plenty of hardware to go with it. If you want the ultimate sonic solution, you know what to do...