The definitive guide to 24-bit FLAC

The definitive guide to 24-bit FLAC

High resolution downloads are changing the way we enjoy music, opening up possibilities undreamed of back in digital’s early days…

CD was revolutionary when it first appeared, just over 30 years ago: none of the surface noise of well-played LPs, no annoying ticks and pops caused by invisible scratches, no need to handle the discs with kid gloves – though the early demonstrations of discs smeared with jam still playing were a little over the top! – and instant access to any track on an album at the push of a button. CD running orders could be programmed, favourite tracks repeated and the duff ones skipped, and in time added features such as CD Text readouts of album, track title and artist would become possible.

For all that, CD was always a compromise, using technology that was only just cutting edge at the time. 30 years on, we can do so much better.

Digital audio encodes the analogue musical waveform, using Pulse Code Modulation. With PCM, the two basic factors that determine the sound quality are bit depth (which determines the quality with which the analogue signal is digitised), and the sampling frequency (which is the number of times per second that the analogue signal is digitised). CD is a 16-bit, 44.1kHz system, what’s needed to improve conformity between the analogue original and the digitised version is a combination of more bits in each samples, and more samples for each second of music: the more bits you use, the more natural the music sounds, and the faster the samples, the wider the frequency range.

CD’s 16-bit/44.1kHz digital system may have been the apparent state of the art in 1982, but it didn’t take long for it to get past its sell-by date. Indeed, some say it was only ever almost good enough for high-quality sound reproduction: Malcolm Hawksford, Professor of Psychoacoustics at Essex University, feels that, ‘It was near the limit, but in my view probably a bit marginal. Ideally, at least 20-bit resolution at 60 kHz sampling frequency would have been better.’



However, 16-bit/44.1kHz is what we got back in 1982, and 16-bit/44.1kHz is what CD still uses more than three decades on: we’ve been trapped in a technology ‘almost good enough’ 30 years ago for all that time, just like we would be with everything else we own if all development had been stopped back then.

Yes, there have been attempts to replace the CD with something better – in the early 1990s not one but two ‘high-resolution’ audio formats appeared, and battle was joined between DVD-Audio and the Sony/Philips Super Audio CD (or SACD), the former offering 24-bit audio quality for greater resolution, improved dynamics and greatly reduced distortion, while the latter’s Direct Stream Digital system used a sampling rate of 2.8224Mhz, 64x that of CD and single-bit sampling.

The new formats also offered the opportunity for multichannel surround sound and greater security and copy protection – one good thing for consumers, it was suggested, and one for the record industry. However, there was a problem or two…

DVD-A discs needed a special player – not just a standard DVD-Video machine – and these were a while coming, while the music retail industry wasn’t keen on stocking releases in multiple formats, and dealing with a hassle of buyers picking up a DVD-A disc by mistake and finding it wouldn’t play on their CD player.

SACD had an answer to that one: its multilayer discs allowed back-compatibility with CD hardware, which just saw them as standard CDs. Only when used in an SACD player was the higher-resolution layer ‘unlocked’. That meant record stores could sell just one disc for SACD and CD buyers, but then the pitching of SACD as a premium medium would have meant CD prices rising, at a time when deep discounting on music was really beginning to kick in.


What has, unfortunately, made a big impression on the market is compressed audio formats, notably MP3: originally used to allow sensible amounts of music to be stored on early personal music players with very limited storage capacity, MP3 can reduce the size of a music file by around 80% by removing most of the sound you can’t hear – quieter sounds masked by louder ones, for example. Unfortunately along the way it also loses quite a lot of the sound quality you can hear, and while the losses may not be so apparent on lower-quality equipment or when played in noisy environments – on headphones in the street or on public transport, for example, or on standard-fit audio systems in many cars –, when you step up to better audio systems it’s all too easy to hear the reduction in quality.

The good news is that while MP3 does’t sound too great, it did open up new channels through which music could be obtained – via online downloads.With those channels opened up, Free Lossless Audio Codec – or FLAC – now makes it possible to download music at CD quality or better, or store your CDs on computer or external storage, while saving up to 50% of the file size without losing any quality.

The clue’s in the term Lossless: FLAC packs music without losing any of the content or quality, and when ‘unzipped’ correctly the file is exactly the same as the original file. And while we’ve seen a number of rival lossless systems, from Apple Lossless (ALAC) to Windows Media Audio Lossless (WMA Lossless), the Free Lossless Audio Codec (FLAC) is the system of choice for many music-loving hi-fi buffs, simply because it’s not tied to any one manufacturer’s systems.

 And it can do more than cut the size of CD-quality files: FLAC can also come in 24-bit form and beyond, as Albert Yong of Bowers & Wilkins explains: ‘The system is so flexible that it can take anything from 4 to 32 bits and sample rates up to 655350Hz in 1 Hz steps.’ he says.

And FLAC, first introduced in 2001, is opening up a whole new world of high-end, high-resolution audio for enthusiasts: 24-bit digital has a theoretical resolution of 144dB (compared to around 96dB in CD’s 16-bit) which is more than enough, given that 130dB is the threshold of pain for the human ear. That means you can get ever closer to the master-tape used in the studio, as well as gaining all the information made possible by the greater data-rates of these high-resolution files: Albert Yong says ‘The difference is in the detail. Sounds generally are more open, and there is an extra level of airiness in the music. Voice and instruments sound closer to live, and more dynamic as well.’

While you can use computer software to rip your CDs into FLAC, there’s also a growing number of sites offering downloads at CD quality and beyond including Society of Sound. We’ve structured our site to make downloading FLAC a breeze. Once you’re signed up as a member you get free albums every month to download; it’s just a matter of downloading a zip file, unzipping it into whichever folder you want on your computer or storage device, and then playing your music using your choice of player software.


If you’re looking to build up a FLAC library of your existing CD collection, then a good starting point for ripping is Exact Audio Copy or dBpowerAMP. These are freely downloadable applications for Windows, commonly thought to be the best sounding and most bug-free. Mac Users can try Max, MacFlac or X Lossless Decoder.

To play the music, there’s a range of software players available, though as you’re using FLAC you’ll find neither iTunes nor Windows Media Player will handle the files directly, so you may have to use a modification to those programs or convert the files to play them. Fluke, for example, is a freeware program that works as ‘plug in’ for iTunes (Mac platform), but it can be buggy.

There are various programs available to convert files to PCM or even Apple Lossless, such as Max for MacOSX, but the best option is probably to use a different player solution, which will play all files in their native format.

On Windows systems, Winamp can play a wide variety of lie formats, and even burn 16-bit files to CD while other good player packages include Foobar2000, Media Monkey, Vox and Nightingale, the last of these being a ‘forked’ version of the now defunct Songbird package, having an interface very similar to iTunes and capable of playing almost any file you throw at it.

Nightingale is also available for Mac OSX, and like other players will hunt down all the music on your computer and add it to its own library if you require. These programs also allow editing of the ‘metadata’ of your music files – the information used to identify the music – should you find a rip or download doesn’t quite have the information you want about artist, album, track and so on.

 Amarra Mini by Sonic Studio is a more sophisticated system that piggybacks on to iTunes, replacing much of its audio code with a superior sounding and more flexible system. Sound is excellent but you pay for it; the basic Junior version which gives FLAC playback up to 24/96 starts at $99.

 Audirvana Plus ( is another fine application that, like Amarra, shuts down certain parts of your computer to minimise drain on CPU resources, to (so the theory goes) give better sound. There’s a free trial download but you’ll have to pay for the full version. It now offers optional integration with iTunes and is a strong, stable performer. For Mac users, its combination of value and performance is currently hard to beat.

 All these programs work as the playback system, but unless you’re happy to listen via your computer’s speakers, or a pair of headphones plugged into it, you’ll need a means of connecting computer to your audio system in order to hear your new high-resolution music collection.

       The simplest way to do this is to take an analogue line output from your computer soundcard. This is likely to have a 3.5mm stereo mini-jack plug, so you’ll need a cable with a 3.5mm stereo plug on one end and a pair of RCA phonos on the other, to connect into a spare line input on your amplifier to system (although systems and amplifiers increasingly have a 3.5mm input on the from for just this purpose. This method will give a reasonable sound, particularly if you have a good quality soundcard, but it’s not ideal computers are electrically ‘noisy’ environments, and it’s best if at all possible to pipe out the digital signal away from the PC or Mac.

       A range of USB DACs are now available to plug straight into your computer and provide an analogue output. Some provide a line output to connect to a hi-fi system, while others allow headphones to be connected for a truly portable high-resolution system, and there’s now a wide range of digital to analogue converters and even amplifiers with USB inputs. Prices start at about £100, while it’s perfectly possible to spend many times that amount on a DAC or headphone amplifier designed for high-resolution music.

Most of these DACs are powered from the computer, and use an asynchronous USB connection, so the high quality clock onboard will control the computer’s digital datastream. This gives tighter, smoother sound compared to standard asynchronous USB, as a result of lower jitter.

       There’s also a small selection of personal players able to play high-resolution FLAC files (among other formats), should you want to take your music library with you on your travels. The most affordable of these starts from under £200.

       Wireless and network streaming open up much greater flexibility. and also allows the streaming of music without the need to have your computer on all the time. You can copy your entire library to a Network-Attached Storage (or NAS) device, which is basically a hard-disk store designed to connect to your wired or wireless network storage, and which can be accessed by multiple players (either standalone systems or network music players designed to connect to a hi-fi system) on your home network.

Several players can be used at once, each playing different music if required: if you want a whole-house music solution, networking is definitely the way to go. Prices for NAS devices start from under £200 for a simple unit, and players at under £400. And the choice out there keeps on growing, as FLAC music catches on.

However, whichever solution you choose, the sound you achieve will only ever be as good as the quality of the files you’re playing, and that’s why we at Bowers & Wilkins, with almost 50 years’ experience of making top-quality premium loudspeakers, take FLAC very seriously. Not only is it convenient, with its shorter download times and almost bombproof content tagging, it’s also upgradable as high-resolution formats evolve: one label – Norway’s 2L – is already offering 24-bit/352.8kHz FLAC files taken from its original DXD masters.

Bowers & Wilkins’s Albert Yong says that ‘FLAC is as good as it can get for now. I think what it brings is not limited to quality of audio, but the added convenience as well’. And whereas once the choice of high-quality music in high-resolution FLAC was limited, initiatives such as the Bowers & Wilkins Society of Sound, are devoted to making more music available, and more people aware of what high-resolution music can bring to their listening experience.

High-quality, high-resolution music, recorded and delivered with fanatical attention to detail and quality – that’s what Society of Sound is all about, and why we’re so keen for you to share our enjoyment of the music we offer.


  • Chris Connaker says:

    Nice article Susanna. It’s wonderful to see B&W talking about 24 bit FLAC.

  • Markus says:

    In the article you were saying:
    “it’s always preferable to isolate the electrically noisy computer from the hi-fi by using an optical digital link.”

    Does this mean you recommend connecting for example a Sonos ZP90 Networkplayer to a Naim SuperNait rather via the optical link rather the digital cable?

  • Mike says:

    Can someone please tell me if the Zeppelin can accept 24-bit using the optical inlet?

    I’m using my computer with the M-Audio transit and can send flac files to the Zeppelin. I’d like to buy some 24-bit recordings and want to know if Zeppelin’s internal DAC can process them.

    I can’t seem to get B&W customer support to respond.

  • Shaun: B&W says:

    Hello Mike

    Thanks for your interest in 24-bit. As you are probably aware our Society of Sound offers a wide selection of albums in 24-bit.

    As for your Zeppelin question, unfortunately the Zeppelin doesn’t support 24-bit.



  • Sam (UnRated NYC) says:

    Hi there. I just wanted to tell you that this article is truly incredible. I’m the editor-in-chief of unrated nyc and I plan on sharing this piece with all my readers. Great work!


  • Andrew Levine says:

    I was irritated when I failed to find any information on FLAC’s developer, then discovered his name is “Josh Coalson” (not Coulson). Other than that I found your article quite interesting. I am not sure I agree with the universal need for >16 bit audio though.

    As a sonophile audio professional I always record at and work with 24 bit audio, frequently at higher sample rates than 44.1, but when I carefully dither my final mixes down to 16 bit (using iZotope’s MBIT+ algorithm or one of the fine Airwindows dithers) I have always been very happy with the results.

    Certainly it’s preferable to leave the material in the original resolution, especially when dealing with the extreme dynamic range and subtleties of classical and avant garde music performed in “real” venues, but for most consumers of the music I produce the dithered version will be way superior than many other off-the-shelf recordings.

    It might boil down to the care you take in training your ears, selecting your gear, preparing for and then recording the acoustic event in the first place, as well as the purity of the processing chain. And let’s not forget that it all begins with good music, performed by inspired musicians. Many thanks to them!


    blumlein records – Andrew Levine

  • Don Baragar says:

    Great article but it does not talk about the effect of amps and speakers on the result. If the frequency response of speaker id 25 hz to 20khz will you notice a difference in 16/44 and 24/96 sound?

  • Andrew Levine says:

    Do we need 24 bit audio for sonic nirvana?

  • SusannaGrant says:

    Hi Andrew,
    Many thanks for your comments – I have amended Josh’s name and apologise for that.
    I thought your last point is particularly salient and is one of the cornerstones of Society of Sound.
    Kind regards,

  • Vereecken says:

    I would highly welcome 96 kHz / 24 bit downloads on the B&W music site.

  • digifish says:

    This is worth a read. I have been producing music for 15 years and concurrently worked in human factors research in the medical device industry, so I am data driven…

    16 bit 44.1 kHz is indistinguishable from higher sample rates and bit depths. That you prefer SACD or some other high-end format is likely that it was produced better in the first place.


  • Paul Dzwonowski says:

    Years ago I was doing the usual browsing at a music shop and stumbled on at the time – for me – an unusual cardboard mini lp CD import from Japan – Charlie Rouse – remastered in 24 bit. At the time I had no idea what 24 bit was – I was just entering the digital world from analog 12” LPS. The CD, however, had a mystique about it compared to all the other “ordinary” plastic jewel cased CDs in the store, and I decided to purchase it and give it a listen. Ever since then I have been an absolute believer in 24 bit recordings and have been collecting the majority of music in 24 bit; never did cross over to SACD format. A few years back I started noticing alot of remastered music coming from Japan in 20 bit format after 24 bit had started. The 20 bit recordings sounded awesome but it puzzled me. The whole process and the art of remastering recordings has since really puzzled me; however aside from the inherit individual preferences in remastering music, why would one remaster a recording in 20 bit instead of 24 bit? Aside from 20 bit vs 24 bit I’d sure like to see a book published to both celebrate and discuss the whole art of remastering recordings!

  • John Clayton says:

    How do I get from MPEG-4 Audio File Format (.m4a)to Flac so I can play the B&W tracks on my winamp

  • digifish says:

    I’m back, Ethan Winer of RealTraps (makers of sound control solutions for studios) just uploaded a fantastic video relevant to this topic from the 2009 Audio Engineering Society.

    Audio Myths Workshop.

    Ethan & co-presenters cover such issues as placebo effects in audio, loudness vs quality, ‘scam’ equipment, dithering, expensive vs cheap A/D D/A converters and more.

    Start at 41m:15s to cover D/A A/D converters and then bit-depth sections. If you have time
    I would encourage you all to watch the whole thing.

  • Brad Jensen says:

    This is exactly what I have been waiting for!!

    FLAC is the best method for storing and listening to music, in my opinion. It’s a free codec, it compresses very well, it decodes well, and it’s lossless. It even holds multi-channel sound.

    If a better version of FLAC ever comes out, it’s easy to just convert those old lossless files to the newer version, without losing any quality!

    I have all of my CDs ripped to FLAC files and mirrored on another hard drive as a backup. :)

    Now, if only we can get mastering engineers / record labels to quit the loudness war and to start master old albums to the best quality they can be, and have those albums released like these 24 bit FLAC files..

  • Paul Stanwix says:

    Dear Audiophiles.

    Music is for listening to, wherever you are. You don’t need to worry about wether you are not hearing all the information. Just listen and enjoy. Even the cheapest CD player from your nearest supermarket does the job, just fine. I started recording my favourite music on a Phillips portable cassette recorder and progressed to a dansette record player when I was a kid. I wasn’t worried about what I wasn’t hearing, I just enjoyed , what was for me, a life changing experience.

    Sorry about that rant! But can any one help me with this problem? I have downloaded the 24 bit version of Peter gabriel’s CD. I want to place it in my i tunes libary. I have downloaded Max as I have a mac, running 10.5.8. What do I have to change the flac file into, to then drag and drop it into my i tunes libary.



  • mackie says:

    Good article. I enjoyed reading it:)

    One note: MP3 is not open source format as Flac is. It’s proprietary and you have to pay for it if you want to use it. As a user you probably don’t pay for it directly ‘couse the company which software/hardware you use payed for it and charged you when you bought their stuff.

    This is also why most Linux distributions did not play MP3 files out of the box. Right now it may changed. Dunno ‘couse don’t use it any more.

  • says:

    whereas FLAC is of course a free, open source system like MP3
    As far as I know, MP3 is not open source, you have to pay a license to Thomson

  • Mick says:

    I wish someone would take the trouble to give this article, with its misplaced links and trailing sentences, a decent edit so it’s actually readable. It would then reflect much better on its host B&W.

    Thanks for the SoS though. I’m enjoying my trial membership.

  • Joe Lubow says:

    Paul Stanwix says:
    “I have downloaded Max as I have a mac, running 10.5.8. What do I have to change the flac file into, to then drag and drop it into my i tunes libary.”

    Paul, Max can convert FLAC 24-bit files directly to Apple Lossless and send them straight to iTunes. In Max Preferences go to the “Formats” pane. Choose “Apple MPEG-4 Audio.” In the “Output” pane choose “Same as Source file” or choose some other place. In the iTunes pane check “use iTunes compatability mode” and “Add output fies to iTunes library.”

    Max will preserve the bit rate and sampling rate, and the Apple Lossless files will be identical in quality to the downloaded flac files. Since iTunes copies the files into your iTunes library, once the tracks show up in iTunes you can delete the Apple lossless files from the output folder, (I have Max set to put them in the same folder as the FLAC files). You could also delete the original flac files, since you could always convert the Apple Lossless files back to flac if you wanted to. I’m superstitous though, and even though they are not only theoretically and practically (to my ears through a Linn system) the same, I back up the flac files to an external drive before deleting them. Since Time Machine backs up iTunes, this is unnecessary, but it just feels weird to me to delete the original files.

    The only catch is that older iPods won’t play 24-bit files. I have an iPhone 3GS, and it plays 24-bit files beautifully, especially hooked up to a good rig, but it won’t play files with a sampling rate over 48k. Scratch My Back, like most of the Society of Sound recordings, is 48k, so you should have no problem; but for recordings with higher sampling rates, you’ll need to downsample. Max can’t do that but XLD is freeware that can. So if you ever find yourself with files sampled faster than 48k and want a version that will play on your iPhone, use XLD to downsample. But save the original higher sample’d file to play through iTunes.

    Depending on why you want them in iTunes, you could also forego iTunes and play the FLAC files directly in Cog or Songbird. But if you want to transfer them into an iPod or iPhone, you’ll need to use iTunes.

    I hope that helped…

  • David says:

    I have downloaded many of the SoS albums and mostly they sound great. However the first track on the Daby Touré & Skip McDonald album (Diaguanu) sounds awful to me. Is there a problem with it? Is the problem my end? The rest of the tracks seem to be OK.


  • David says:

    Sorry – I should have said, it is the 24-bit FLAC version that I have.

  • Matt says:

    Besides the Transporter from Slim (now Logitech) Olive seems to develop a 24-bit music server ( …

  • Josh says:

    Flac shmac … it is still a PCM format. I have been quite impressed with some 96 kHz/24 bit recordings, but the most impressive recordings are pure DSD recordings on SACD. The article also seems to place an undue emphasis on bit rates –> it seems to me that the real gains in removing digital artifacts comes from high sampling rates … not from high bit rates. There is also vastly more hi-rez content out there on SACD (over 6000 titles now) than in FLAC (which is currently in the low hundreds).

  • Paul C says:

    Thank you for this excellent article B&W, and the useful advice it contains.

    I have to say that to my ears, the difference between 16bit/44 and 24bit/88 is enourmous. I am sitting here listening to a previously downloaded 24bit wma sampler including music which I would never normally listen to and it is like disovering music for the first time.

    This is the first time that the sound coming out of my speakers from a digital source is genuinely enjoyable.

  • Paul L says:

    I hope some people find this link interesting

    24/88, 96 sounds to me more natural especially on live music recorded in places with certain acoustical character. Hi-End should about preserving the perfomance at the time and space I took as faithfully as possible, but there is always a limit to technology we use, …what is real, anyway.

  • Graham W says:

    Does anyone know if the MM-1 speakers have a 24 bit DAC. The only information I have found suggests that the DAC is 16 bit only.

  • Andrew Henry says:

    Aren’t HiRes fans in a bit of a conundrum at the moment? If we didn’t have cheap computer based music servers to connect to our hifi systems, we’d all have SACD or DVD-Audio players, but these days, downloadable content and music servers are all the rage, and what’s better than ripping your entire music collection to a computer so you don’t have to buy an expensive CD changer or keep swapping discs??

    But you can’t rip SACD!! Is it worth the purcahse if you want a computer based music library? You can rip DVD-Audio… just… with a moderate splattering of hassle (even multi channel). But it’s certainly not as “accessible” to rip HiRes music discs as it is to rip standard CD’s. Isn’t the “best” option, the most “future-proof” one, to download HiRes FLACs where available?

    I have a Pioneer DVD player that’s nearly 10 yrs old that can play DVD-A and SACD, and I’ve just started buying HiRes discs (1-2 DVD-A’s and a few more SACD’s, but I know I can never have these in my digital music collection, so it puts me off buying more physical discs.

    Anyone else have this problem?

  • SusannaGrant says:

    Hi Graham,
    The MM-1s do have a 16-bit DAC.

  • SusannaGrant says:

    Hi Graham,
    You’re correct, the MM-1s do have a 16-bit DAC.

  • Jan says:

    @ Andrew Henry

    Hello Andy, I am convinced that there should be no problem to record your hi-res albs to your computer collection. Your CD/SACD certainly has a digital output has it? If so you can easily connect the player with pc using some audio card such as M-AUDIO to grab your hi-res signal.


  • Seb says:

    @Jan : Sony forbids SACD players from offering any hi-res digital output (IIRC, they’re limited to 16/44.1).

  • Matt says:

    Is it worth recording vinyl music to a 24bit digital flac file as oppose to 16bit? If it is can you explain why?

    The reason i ask is because i thought vinyl has a depth of around 12bit??

    Look forward to your comments :-)

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