High-resolution audio (HRA) has emerged as arguably the ultimate sonic selection for digital music fans, but what's it all about, what do you need and how can you get it? Allow us to explain.

2015 saw high-resolution audio (HRA) hit the mainstream, thanks to the release of more devices and services that support the audio format.

From Neil Young's PonoPlayer to hi-res audio support on the Sony Xperia Z3 and hi-res streaming on Qobuz, 2015 proved there was plenty of benefits to HD audio.

Digital downloads from sites such as Amazon and iTunes, and streaming services such as Spotify use compressed file formats with relatively and low bitrates, such as 256kbps AAC files on iTunes and 320kbps MP3 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 on the bus when you're listening to your iPod or smartphone, but serious music fans should want better. This is where high-resolution audio – or HRA, the term coined by the Consumer Electronics Association – steps in.

Astell & Kern, LG, Samsung, SonyFiiO and Pioneer are just some of the companies to have launched hi-res audio compatible products so far, while several download sites now offer better-than-CD quality music files, with the likes of HDtracks and Qobuz now live in the UK. HRA also has the support of major 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? All your questions and more are answered here. 

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 or 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 meanwhile, 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 new 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, ensuring your tracks have artist and title information. There's a healthy debate on the What Hi-Fi? Forum on the subject of FLAC vs. WAV.

Of course, as well as downloading your music in these superior formats, and now streaming, 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. 

As always, though, there are some people who can't hear a difference. So, if you can't see or hear a difference, save your money… 

MORE: Hi-res audio - the science behind the numbers

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:

HDTracks

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 seamles digital music experience across PC, Mac, Android and iOS.

MORE: HD Tracks review

 

7Digital

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

 

Naim Label

 

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 Records

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 £18, or £10 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.

MORE: B&W Society of Sound review

 

Qobuz

French website Qobuz launched in the UK back in August 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

 

Technics Tracks

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 

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 - and delivers a bold and informative sound. 

MORE: Onkyo Music 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 in this country.

With all sites, make sure it’s clear what file format and bitrate you are buying - and let us know your experiences with using these and any other HRA websites in the comments below.

Hi-res streaming?

Tidal and Meridian demo high-res streaming

We’ve now seen the arrival of CD-quality streaming services, with Tidal and Qobuz launches offering lossless audio streams.

This delivers a step up in quality over established services such as Google Play Music, Rdio and the market-leader, Spotify. And indeed the new Apple Music streaming service.

But it's not strictly hi-res audio - that, remember, refers to better-than-CD-quality files.

It's also possible to stream hi-res audio on Android, and now Apple smartphones. Qobuz has updated its mobile app for Android smartphones to allow you to stream any 24-bit hi-res songs you've already paid for. Of course, you'll need a smartphone that supports the high-resolution audio format, such as the Sony Xperia Z5, LG G5 and Samsung Galaxy S7 series.

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 relability, although you will need to pay £8 to unlock the HD section. You can read a full guide to playing hi-res music on your iPhone here.

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. Thankfully, there's a new file format in town, developed by 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. 

MORE: MQA Audio - What is it? How can you get it?

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. 

As yet, 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. 

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.

Complete systems, such as the Monitor Audio MA100, now support hi-res audio (as well as wireless streaming features), while companies such as Sharp have also got in on the act.

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.

You will need a high-resolution audio player, as not all music software is compatible. iTunes will play hi-res files but not FLAC files, for example.

If you’re on a Mac, you can try Amarra or Channel D's Pure Music. We also hear differences in sound quality, so it's worth experimenting. On a PC? Try JRiver Media Center

MORE: What are high-resolution headphones?

High-res music on mobile

Hi-res audio isn’t confined to the dedicated hi-fi market. Several of the latest smartphones play music in sparkling 24-bit/192kHz quality, including the LG G5Sony Xperia Z5 and Samsung Galaxy S7.

The iPhone 6 sadly doesn't support hi-res audio out of the box but there are apps you can download to your phone (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 and 3.5mm headphone port don't support the format. 

You can use a pair of Lightning headphones, such as the Philips M2L or Audeze EL-8 Titanium or Sine, more pairs are expected to be released as we approach the launch date of the iPhone 7. Alternatively, you can connect a DAC, such as the Chord Mojo - you'll need Apple's iPad to camera USB adapter - and then plug in your regular headphones to listen to hi-res audio. 

It's also possible to connect devices via the Lightning connector rather than the headphone jack to send a digital audio signal.

The Philips M2L headphones are one of the first to use the Lightning connection, bypassing the iPhone’s internal DAC to use instead their own hi-res capable DAC.

And Qobuz has provided a world first for Android mobile users: the ability to stream hi-res music on your phone via its streaming service.

Best hi-res audio streamers

Best music streamers under £600

Bluesound Node 2

Five stars

Tested at £430 / Best price £429 at Sevenoaks

“A wonderfully expressive and detailed sound served up with a brilliant design and extensive feature list”

 

Pioneer N-50a 

Five stars

Tested at £500 / Best price £349 at Amazon

“A superstar, improved. Pioneer has done it again.”

 

Best music streamer under £1000

Cambridge Audio CXN 

Five stars

Tested at £700

“A stylish, feature-packed streamer that sounds great and is a joy to use.”

Best music streamer under £1500

Cyrus Stream Xa

Five stars

Tested at £1250 

“If you're looking for a premium streaming option, the Stream Xa is a fantastic proposition.”

Best music streamer £2000+

Cyrus Stream XP2-QX

Five stars

Tested at £2300

“This superb streamer sounds absolutely fantastic”

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.

 

Acoustic Research M2

Four stars

Tested at £900

If you’re looking for a premium portable hi-res player, then the M2 deserves a listen. 

 

Astell & Kern AK Jr

Five stars

£400 / Best price £330 at eGlobal Central

This hi-res player isn’t cheap, but its build quality and performance make it a formidable, portable pleasure.

 

Sony NWZ-A15

Four stars

£170 / Best price £159 at Amazon

If you’re not after flashy features and merely want to dip your toe into the high-resolution water, this is a very good place to start.

 

See all our portable music player reviews 

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 current multi-room audio champion, Sonos.

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. 

MORE: See all our Bluesound reviews

Sonos can only stream in CD-quality 16-bit/44.1khz.

Other multi-room audio systems have followed the lead of Bluesound, with systems such as the LG Music Flow, Lenco PlayLink, Harman Kardon Omni and Monster SoundStage all offering hi-res support on their new wireless speaker systems.

MORE: Multi-room audio: everything you need to know

What's next?

Since receiving its own dedicated zone at CES, high-resolution audio gained a lot of traction through 2015 and into this year.

Manufacturers including Bowers & Wilkins, Naim and Linn have been pushing for and producing high-resolution audio products for some time. We’ve now seen mass-market heavyweights such as Sony, LG and Samsung 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 brings to music listening. There's plenty of content out there, there's plenty of hardware to go with it and hi-res scene looks set for further growth through 2016 and into 2017. 

OPINION: The science behind the hi-res audio numbers