After years of niche positioning in the music world, high-resolution audio (or 'hi-res audio') has finally hit the mainstream, thanks to a huge raft of support from streaming services (such as Apple, Tidal and Amazon Music HD) and products (from smartphones to most digital hi-fi components) alike.
But should you care about hi-res audio? If you want the best digital music experience possible or at least better sound quality than you're currently used to (and why wouldn't you?), then yes; hi-res audio is definitely worth investigating.
It can be a daunting prospect. After all, what exactly constitutes hi-res audio, what do all the different file formats and numbers mean, where can you download or stream these higher-quality files, and what devices do you need to play it?
Where, we hear you ask, do you even begin?
That's where we come in. Our handy guide will take you through the ins and outs of hi-res audio. By the end, we hope you'll know everything you need to know (and then some) and will be well on your way to enjoying your new and improved sonic lifestyle.
What is high-resolution audio?
Unlike high-definition video, there’s no single universal standard for hi-res audio. In 2014, the Digital Entertainment Group, Consumer Electronics Association and The Recording Academy, together with record labels, formally defined high-resolution audio as “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".
In its simplest terms, hi-res audio tends to refer to music files that have a higher sampling frequency and/or bit depth than CD, which is specified at 16-bit/44.1kHz.
Sampling frequency (or sample rate) refers to the number of times samples of the signal are taken per second during the analogue-to-digital conversion process. The more bits there are, the more accurately the signal can be measured in the first instance, so going from 16-bit to 24-bit can deliver a noticeable leap in quality. Hi-res audio files usually use a sampling frequency of 96kHz or 192kHz at 24bit. You can also have 88.2kHz and 176.4kHz files too.
Hi-res audio does come with a downside, though: 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 or be cumbersome to stream over your wi-fi or mobile network. Thankfully, storage is much cheaper than it used to be, so it's easier to get higher-capacity devices. And streaming technologies, like MQA (see below), have found a way to help tackle that.
That's not all: there are also several different hi-res audio file formats to choose from, all of which have their own compatibility requirements.
They include the popular FLAC (Free Lossless Audio Codec) and ALAC (Apple Lossless Audio Codec) formats, both of which are compressed but in a way that means that, in theory, no information is lost. They are 'lossless' as opposed to 'lossy'. Other formats include the uncompressed WAV and AIFF formats, DSD (the format used for Super Audio CDs), and the more recent MQA (Master Quality Authenticated).
The relative merits of each of the formats can be argued, but the most crucial issue will be the file's compatibility with your chosen products and software.
Here's a breakdown of all the main file formats:
MP3 (not hi-res): Popular, lossy compressed format ensures small file size, but far from the best sound quality. Convenient for storing music on smartphones and iPods, but doesn't support hi-res.
AAC (not hi-res): An alternative to MP3s, it's lossy and compressed but sounds better. Used for iTunes downloads, Apple Music streaming (at 256kbps) and YouTube streaming.
WAV (hi-res): The standard format all CDs are encoded in. Great sound quality but it's uncompressed, meaning huge file sizes (especially for hi-res files). It has poor metadata support (that is, album artwork, artist and song title information).
AIFF (hi-res): Apple's alternative to WAV, with better metadata support. It is lossless and uncompressed (so big file sizes), but not massively popular.
FLAC (hi-res): This lossless compression format supports hi-res sample rates, takes up about half the space of WAV, and stores metadata. It's royalty-free and widely supported (though not by Apple) and is considered the preferred format for downloading and storing hi-res albums.
ALAC (hi-res): Apple's own lossless compression format also does hi-res, stores metadata and takes up half the space of WAV. An iTunes- and iOS-friendly alternative to FLAC.
DSD (hi-res): The single-bit format used for Super Audio CDs. It comes in 2.8MHz, 5.6MHz and 11.2MHz varieties, but isn't as widely supported as some of the formats above.
MQA (hi-res): A lossless compression format that efficiently packages hi-res files with more emphasis on the time domain. Used for Tidal Masters hi-res streaming, and product support is picking up pace.
- MP3, AAC, WAV, FLAC: all the audio file formats explained
What’s so good about hi-res audio?
The main claimed benefit of high-resolution audio files is superior sound quality over compressed audio formats such as MP3 and AAC.
Downloads from sites such as Amazon and iTunes, and streaming services such as Spotify, use compressed file formats with relatively low bitrates. For example, Spotify (which unlike Amazon Music and Apple Music has notoriously not yet ventured into better quality) uses 320kbps Ogg Vorbis streams.
The use of lossy compression means data is lost in the encoding process, which in turn means resolution is sacrificed for the sake of convenience and smaller file sizes. This has an effect upon the sound quality – those formats aren't telling the full story of our favourite songs.
This might be fine when you're listening to Spotify playlists on your smartphone on the bus on the morning commute, but serious audiophiles and music fans should want better. This is where high-resolution audio comes in.
To illustrate why it should sound better than MP3, for example, let’s compare the relative bitrates. The highest quality MP3 has a bitrate of 320kbps, whereas a 24-bit/192kHz file has a data rate of 9216kbps. Music CDs are 1411kbps.
The hi-res 24-bit/96kHz or 24-bit/192kHz files should, therefore, more closely replicate the sound quality the musicians and engineers were working with in the studio. And they could be that very same recorded file, too. These files are labelled as "Studio Masters" in some cases.
With more information on the file to play with, hi-res audio tends to boast greater detail and texture, bringing listeners closer to the original performance – provided their system is transparent enough.
What do I need to play hi-res audio?
There's a huge variety of products that can play hi-res audio. It all depends on how big or small you want your system to be, how much your budget is, and what method you'll mostly be using to listen to your tunes. But it's never been easier to get involved, now that plenty of the digital and streaming ecosystem supports hi-res, including popular streaming platforms such as Google Chromecast (although not AirPlay 2, which currently has a limit of 16-bit/44.1kHz).
These days, even, you don't have to completely abandon your vinyl collection to go hi-res, either; turntables such as the Sony PS-HX500 let you digitise your vinyl collection by ripping your record tracks into hi-res audio files.
If you're going portable, smartphones are increasingly supporting hi-res playback. This is restricted to higher-end Android models, though – Apple iPhones so far don't support hi-res audio out of the box (though there are ways to play hi-res music and lossless audio on your iPhone by using the right app, and then either plugging in a DAC or using Lightning headphones with the iPhones' Lightning connector).
Phones that have USB-C sockets instead of 3.5mm headphones jacks for music playback – as is becoming the norm – can boost their USB-C output with discreet DAC-toting adapters such as the Zorloo Ztella USB-C DAC and Astell & Kern AK USB-C Dual DAC Cable.
Hi-res audio can be streamed wirelessly between phones and headphones/speakers that support the latest Bluetooth codecs (such as aptX HD Bluetooth), but not truly losslessly (i.e not without compression). Qualcomm says it has found a way to transmit CD-quality music losslessly with its upcoming Snapdragon Sound solution, but it could be some time before that's the case with hi-res.
Portable music players
Alternatively, there are plenty of dedicated portable hi-res music players such as various Sony Walkmans and Award-winning Astell & Kerns and Cowons that offer more storage space and far better sound quality than a multi-tasking smartphone. More digital players than not support hi-res audio, although again an Apple product is the exception, this time the iPod Touch.
For a desktop solution, your laptop (Windows, Mac, Linux) is a prime source for storing and playing hi-res music (after all, this is where you'll be downloading the tunes from hi-res download sites anyway), but make sure the software you use to play music also supports hi-res playback. Apple iTunes, for instance, doesn't support it, even if your MacBook does, so you'll need to buy and download separate music playing software. The likes of Channel D's Pure Music and Amarra are worth considering for a Mac. On a PC? Try JRiver Media Center.
We wouldn't just rely on your computer or phone's internal DAC to do hi-res audio justice, either. A USB or desktop DAC (such as the Chord Mojo 2, Cambridge Audio DacMagic 200M and AudioQuest DragonFly Cobalt) is a good way to get great sound quality out of hi-res files stored on, or streamed from, your computer or smartphone (whose own audio circuits don't tend to be optimised for sound quality). Simply plug a decent digital-to-analogue converter (DAC) in between your source and wired headphones for an instant sonic boost.
- The best DACs you can buy: USB, portable and desktop DACs
If you're after a proper hi-fi setup, you'll need to look into music streamers that support hi-res, and highly recommendable contenders include the Bluesound Node, Cambridge CXN V2 and NAD C 658. This is especially if you'll be storing your growing hi-res library on a NAS (Network Attached Storage, essentially a hard-drive with processing built-in), which we would recommend.
There are plenty of other products that also support hi-res playback, including DAC/streamer combos (Moon Neo Ace), speaker systems with everything built into them (KEF LS50 Wireless II), just-add-speaker systems (Marantz PM7000N) and current AV receivers (Denon AVC-X3700H).
Even Sonos multi-room systems now support hi-res (via Qobuz and Amazon Music). Rival multi-room brands such as Bluesound and Denon HEOSw offer hi-res playback across their range of connected products too.
At the higher end of the wireless speaker market, hi-res support is the norm. The likes of the Naim Mu-so 2, Naim Mu-so Qb 2nd Generation, Linn Series 3 and Bowers & Wilkins Zeppelin are all able to handle hi-res file playback over wi-fi. It isn't a common feature at the lower end of the spectrum (the Sonos One supports it, mind), but there's a strong argument that they don't have the quality of hardware to warrant it anyway.
- The best multi-room systems on the market
Where can I buy and download hi-res music?
Now that you're armed with all this information on hi-res music, your next question should be: where can I get all these glorious hi-res music tracks?
There are currently a handful of UK download sites that let you buy and download single tracks and full albums in various hi-res formats. There are also plenty of US and European sites, though not all of them let you purchase from the UK.
Major music labels such as Sony, Warner and Universal have made their extensive music catalogues available to these hi-res download services – 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. Ultimately, you may end up with a favourite go-to site, but even then, it's worth checking across the different sites for the same album or track, too, as some stores can offer better prices than others.
Here are the top UK hi-res download sites:
With a strong catalogue offering hi-res music from all genres and a website that makes buying music easy, 7digital is an excellent all-rounder. There's an accurate search function and the website is simple to navigate. You can easily spot hi-res recordings thanks to a '24bit FLAC' badge on an album or song's thumbnail, and there's also a dedicated hi-res section. The sole drawback is that it only offers downloads in the FLAC format. Prices are affordable, though, and you can buy individual tracks as well as full albums.
Music discovery and front-end intuitiveness get full marks on French download store Qobuz. Both the website and dedicated app are easy to navigate, and you can search by genre or new releases, which can be sorted by sample rate. There is a strong Francophile focus, although the catalogue is growing more varied every day. Pricing is competitive, but if you opt for the hybrid download-and-streaming Sublime+ service you do get discounts when buying hi-res albums.
HDtracks may be one of the most established hi-res download stores, but it's in need of a refresh in looks and catalogue. It can feel aimed at an older audience (there's strong focus on jazz, classical and dad rock), which can be off-putting for wider audiences, especially fans of more current, popular music. On the other hand, whereas other download sites offer FLAC as default, HDtracks lets you choose between FLAC, ALAC, WAV and AIFF (and the sampling rate for each) before downloading. There's a selection of DSD tunes, too, which is great for audiophiles.
- Starting from scratch? Here's how to build the perfect hi-fi system
Where can I stream hi-res music?
Not ready to download hi-res files, or simply prefer streaming? Tidal and Qobuz streaming services have offered hi-res and CD-quality streams for years, but now the likes of Amazon Music and Apple Music have caught up, meaning hi-res streaming is now firmly in the mainstream domain (even without Spotify's help).
Tidal and MQA's partnership has brought us one step closer to mainstream hi-res music streaming. You'll need to subscribe to Tidal's HiFi Plus tier to unlock the Masters section, and then you can stream hi-res MQA files through the desktop app and Android/iOS mobile apps as well as Dolby Atmos songs.
Tidal's catalogue of MQA files is now well into the millions, with a resolution of up to 24-bit/96kHz (any 192kHz files will be unpackaged to 96kHz by MQA's core decoding). With the right kit, the streamed tunes sound great, too. It's a solid foundation from which the hi-res streaming experience can only evolve.
Qobuz Studio Sublime / Studio Premiere
Qobuz strikes again here and says its hybrid download-and-streaming Studio Sublime tier is '"the best music subscription in the world." This top-tier package offers hi-res streaming up to 24-bit/192kHz files (as well as CD quality tracks) on its desktop and mobile apps, with its 50-million-track catalogue including more than 240,000 hi-res albums. You can, however, opt solely for streaming rights via its cheaper Studio Premiere option.
Amazon Music HD
Amazon's arrival into the hi-res streaming service world at the end of 2019 largely marked hi-res streaming going mainstream. It entered as the cheapest hi-res service of the three that existed at the time (above), but when Apple Music came onto the hi-res scene in 2021 and undercut it, Amazon lowered it subscription price to match it. In fact, for Amazon Prime members, it's the cheapest hi-res service out there. The value-packed streaming service is up there with the best thanks to its intuitive desktop and mobile apps, good CD-quality and hi-res library, and excellent value.
Apple changed the game in the summer of 2021 by offering subscribers hi-res (and spatial) audio tracks at no extra cost. Its hardware may not be the best advocate of hi-res audio, but its Music offering (and Apple TV+ video service) is big on quality. Die-hard Spotify fans who own Apple kit may even be tempted to switch allegiance now – and we wouldn't blame them.
Currently, until the long-delayed Spotify HiFi tier launches, the world's most popular streaming service does not yet support CD-quality – let alone hi-res – streams. Deezer, meanwhile, tops out at CD quality.
What's next for hi-res audio?
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.
Even without support from Spotify and Apple hardware, there are plenty of increasingly affordable ways to enter the hi-res audio world. Interestingly, immersive audio formats such as Sony 360 Reality Audio, Dolby Atmos Music and Apple spatial audio are also making headway in offering higher quality, if not necessarily 'hi-res', music experiences, so they're also options for melomaniacs to explore.
The next and biggest obstacle for hi-res audio to overcome is its incompatibility with lossless Bluetooth transmission and thus wireless headphones. If the two went hand in hand, hi-res audio consumption would no doubt skyrocket. Apple and Sonos are reportedly looking at alternatives to Bluetooth, so this could help.
Still, with the greater accessibility of hi-res from both a software and hardware point of view, more people are able to learn and understand exactly what high-resolution audio is, and the benefits it can bring to music. There's now plenty of content out there, and plenty of products to play it.
So if you want the ultimate sonic solution, you know what to do.