2015 has seen high-resolution audio (HRA) hit the mainstream, thanks to the release of more devices and services that support the audio format.
But how did it all start and where is the market heading?
As the music industry shifted away from physical media such as CD and vinyl (the vinyl resurgence not withstanding), many of us moved to digital downloads from sites such as Amazon and iTunes, and latterly streaming services, such as Spotify.
These sites use compressed file formats with relatively and low bitrates, such as 256kbps AAC files on iTunes and 320kbps MP3 streams on Spotify.
And with regards to sound quality, these formats aren't telling the full story of our favourite songs. 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.
This might be fine on the bus when you're listening to your iPod or smartphone, but some serious music fans want better. This is where high-resolution audio – or HRA, the term coined by the Consumer Electronics Association – steps in.
Astell & Kern, LG, Samsung, Sony and FiiO are just some of the companies to have launched high-resolution 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? Don't worry – all your questions and more are answered on this page.
What is high-resolution audio?
Before we address this, 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 high-res audio.
But it tends to refer to audio that has a higher sampling frequency and bit depth than CD, which is 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 means 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 see 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-res 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 that (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.
FLAC tends to be the most popular, 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 high-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.
Though, as always, there are some people that can't hear a difference. As with all the products we review, if you can't see or hear a difference, then save your money...
Where to buy and download high-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 uncomprossed 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 high-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.
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. High-res albums cost between £9.99 and £16.99.
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.
Another hi-fi brand that turned its hand to hi-res downloads, B&W’s site boasts 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.
Neil Young's long-awaited Pono high-res service looks finally set to launch, with news that a Kickstarter campaign will make the PonoPlayer available to buy. The PonoMusic service promises DRM-free high-res downloads from major and independent labels and there's a dedicated music management software application, too. You can read our first impressions of the Pono PonoPlayer for more details.
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.
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.
Onkyo Music meanwhile claims 'hundreds of thousands' tracks for download, and is now live in the UK, US and Germany.
2L – Norwegian site offering up to 24-bit/96kHz and multichannel DSD
7Digital – Offers 24-bit FLAC downloads
Gimell – Studio Master 5.1 downloads in 24-bit/96kHz
HD Klassik – Classical music high-res downloads
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.
Tidal and Meridian demo high-res streaming
But it's not strictly high-res audio, which refers to better-than-CD-quality files.
There is one exception - if you have an Android phone you can stream high-res audio on Qobuz.
Tidal and Meridian have also successfully demonstrated streaming high-res audio, using Meridian's MQA format. But there's no sign of an official public launch yet. It could be that Meridian's MQA format is key for any further high-res streaming services.
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 high-res files directly from USB storage devices or from a networked PC via Ethernet.
You can also play high-resolution audio stored on a PC by connecting it to a USB DAC like the Arcam irDAC (pictured, above), the Naim DAC-V1 or the T+A DAC 8, then feeding it to a power amp, powered speakers or headphones.
You can even buy dedicated headphone amps with built-in DACs that handle high-res audio. The ever-popular Sonos system supports WAV and AIFF files but only up to uncompressed CD quality.
However, you will need a high resolution audio player, as not all music software is compatible. iTunes will play high-res files but not FLAC files, for example.
High-res music on mobile
High-res audio isn’t just confined to the hi-fi market. Several of the latest smartphones play music in sparking 24-bit/192kHz quality, including the LG G3, Sony Xperia Z3 and Samsung Galaxy Note 4, while the Onkyo HF Player app allows you to play high-res music on any compatible mobile phone.
The iPhone 6 sadly doesn't support high-res audio out of the box but there is the potential to connect devices via the Lightning output rather than the headphone jack to send a digital audio signal.
The Philips M2L headphones are the first to use the Lightning connection, bypassing the iPhone's internal DAC to instead use their own high-res capable DAC.
And Qobuz has provided a world first for Android mobile users: the ability to stream high-res music on your phone via its streaming service.
More after the break
Best high-res audio streamers
Best portable high-res music players
High resolution audio doesn't have to be saved for home listening anymore. 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 high-resolution music players. Here are our favourites, in price order. Click through for the full reviews, latest prices and more details.
If you're looking for a premium portable high-res player, then the M2 deserves a listen.
We’re very impressed with the Astell & Kern AK100 MkII, but there are issues. We’re pleased to see DSD support, but that’s offset by the sluggish interface.
One of the best portable high-res music players on the market today, the F886 delivers high-resolution tracks with supreme precision. The fact it's built around the Android operating system, granting access to the app store and web browsing, makes it a lot more desirable.
MORE: Sony NWZ-F886 review
£170 / compare prices
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.
Upcoming music players
Astell & Kern AK240
Unveiled at CES, the flagship Astell & Kern AK240 was one of our Stars of CES winners, and features a 256GB internal memory and a microSD card slot supporting up to 64GB of extra storage. It can play DSD files without having to convert them, and will also stream music from a NAS device.
Sony's new £950 NWZ-ZX2 Walkman was one of the big announcements at CES 2015. The initial signs appear promising - but then for this sort of money you'd certainly hope so.
Just how good it is and whether it can justify the price tag for a portable music source remains to be seen. You can read our ZX2 hands-on review.
First impressions of the PonoPlayer, complete with an unboxing video, this is the portable high-res music player that's part of Neil Young's PonoMusic high-res ecosystem. Read our PonoPlayer hands-on review.
Multi-room high-resolution audio
Multi-room audio products have seen a major boost in 2015, with many manufacturers looking to expand their product arsenal's or new manufacturers looking to steal the limelight away 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 by the results. Products in the range include the Node 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 high-res support on their new wireless speaker systems.
Since receiving its own dedicated zone at CES, high-resolution audio gained a lot of traction in 2014 and in to 2015.
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 - and now we have the hardware to go with it.
Moving through 2015, we expect more manufacturers to produce more affordable high-res audio products, as high-res becomes a standard feature on music players, streamers and more, giving consumers the choice to get involved, should they value the potential jump in audio quality.