Intro to high-resolution audio
Music downloads that get back to great sound
Steve Kindig has been an electronics enthusiast for over 30 years. He has written extensively about home and car A/V gear for Crutchfield since 1985. Steve is also a volunteer DJ at community radio station WTJU, where he is a regular host of the American folk show "Atlantic Weekly," as well as the world music program "Radio Tropicale."
More from Steve Kindig
Close your eyes and the musicians are in the room
The performance is spread out before you, complete in every detail. The singer takes a breath between phrases, the guitarist's fingers squeak lightly as they travel up the fretboard, and the drummer coaxes a delicate, shimmering rhythm from his ride cymbal.
Sure, you need good equipment to hear these nuances, but you also need a high-quality source. This is why we're so excited about high-resolution audio. With a level of sonic detail that's better than CD, downloadable high-res music files can deliver sound so real, you feel like you're sharing the studio or the stage with your favorite musicians. Once you've had this kind of fully engaged listening experience, it's hard to go back to ordinary sound.
Leaving limitations behind
You can’t beat the convenience of digital music files. But low-resolution files (like the ones you get from the iTunes® store) can sound thin and flat when played through a good audio system.
If you want convenience and good sound, you owe it to yourself to try high-resolution music downloads. With the right setup, you’ll get sound that’s as good as or better than CDs.
High-res digital music has been popular with audiophiles for years. There have been disc formats like Super Audio CD (SACD), and in recent years, online music stores specializing in CD-quality-or better downloads have emerged.
Now high-res audio seems ready to break out to a wider audience. Music labels are offering thousands of titles across every music genre. The gear and software you need to play high-res files are getting friendlier and more affordable. But there are some things you need to know before you dive in. This article will help you understand the buzzwords and show you how to enjoy high-resolution audio.
What is high-resolution audio?
When you download music from the iTunes® Store or Amazon, you’re paying for “lossy” compressed files with a bit-rate of 256 kilobits-per-second. You won’t find CD-quality or high-res files at either site. But when you browse high-res online music stores like HDtracks, you’ll find only CD-quality or better downloads. These files cost more than MP3s, but the difference in sound quality can be startling.
Typical lossy music downloads only have a fraction of the music information contained in a CD track. And high-resolution audio can provide much more musical detail than CD. (Bit-rates are listed in kilobits-per-second.)
High-resolution audio file types
When you purchase high-res music tracks you can usually choose from several file format options (see below). High-res players and software don’t always support all file types, so make sure you choose files that are compatible with your setup. Beyond compatibility, keep in mind that “uncompressed” audio files will take up around 50% more storage space on your computer or hard drive than “lossless compressed” files. Uncompressed and lossless files should theoretically sound the same.
PCM – the basic audio file format for digital music, whether it's MP3, CD-quality, or high-resolution.
WAV – the main audio format for Windows-based computers.
AIFF – the main audio file format for Apple® computers.
DSD – the only non-PCM-based file type listed here. This format stores audio in a fundamentally different way than PCM.
FLAC – an increasingly popular lossless audio option, however, it’s not compatible with some music playback software, including iTunes.
ALAC– aka Apple Lossless, the main lossless audio option for Apple computers.
Getting comfortable with the numbers
Besides choosing the file format, you can also usually have a few resolution options. For digital audio files, there are two key pieces of information: “word-length” and “sampling frequency.” CD has a word length of 16 bits and a sampling frequency of 44,100 Hertz (a Hertz equals one cycle per second). You typically see resolution specs abbreviated, so that CD-quality files are listed as 16-bit/44.1kHz.
You can achieve better-than-CD sound quality through higher word lengths, higher sampling frequencies, or both. High-res audio is typically 24-bit, with a sampling frequency of 88.2kHz or higher. Except for DSD, all of the file types we’ve mentioned so far use the same basic digital audio format, called PCM. PCM takes snapshots of the musical waveform – the word length measures how detailed the snapshot is, and the sampling frequency tells you how many snapshots per second. Taking more detailed snapshots, and many more of them, can produce a more accurate “picture” of the musical performance, but all that extra data creates a much bigger file. A 24-bit/96kHz music file will take up about three times more hard drive space than a CD-quality file.
DSD is a digital audio format that stores audio differently than PCM. It’s a “1-bit” system, which means that the music signal is processed as a stream of single bits rather than multi-bit chunks. A few websites offer DSD music downloads, and a small but growing number of components can play DSD files.
|File type||Word length||Sampling rate||Bit rate||Albums per 1TB of storage|
|Typical lossy music download||N/A||N/A||256 kbps||10,500|
|24/88.2 download||24-bit||88.2kHz||4233 kbps||690|
|24/96 download||24-bit||96kHz||4608 kbps||630|
|24/176.4 download||24-bit||176.4kHz||8467 kbps||350|
|24/192 download||24-bit||192kHz||9216 kbps||320|
|DSD 64 download||1-bit||2.8MHz||5644 kbps||500|
|DSD 128 download||1-bit||5.6MHz||11,288 kbps||250|
MQA: A new approach to digital music playback
So far, we've been talking about PCM- or DSD-based high-res files. These formats sound terrific, but the music files are huge. A new digital encoding and decoding system called MQA (Master Quality Authenticated) aims to deliver high-res or better sound quality using bit rates that are low enough for music streaming services. At this point, MQA is only available on a very limited selection of equipment and content.
One of MQA's co-developers is Bob Stuart of Meridian Audio, the famed British high-end company. MQA is backward-compatible with existing audio gear and music distribution infrastructures. MQA files are formatted as standard PCM files (FLAC, AIFF, WAV, etc.). If you don't have an MQA DAC, the file will play on any regular DAC with slightly-better-than-CD sound quality. But if you have an MQA-capable DAC, the file will "unfold" the high-resolution information and deliver the resolution of the original studio master.
We carry one MQA-compatible portable player, the Pioneer XDP-100R. For a detailed explanation of how MQA works, see Robert Harley's excellent article in the May/June 2016 issue of The Absolute Sound.
Where to find high-res music
If you've never heard high-resolution audio, you can visit some of the high-res music stores listed below. Most of these websites offer a few high-res music files you can download and listen to for free.
HDtracks — www.hdtracks.com
The world’s largest selection of high-res audio downloads; file formats: WAV, AIFF, ALAC, FLAC
Acoustic Sounds — store.acousticsounds.com/superhirez
Wide selection of audiophile recordings; formats: FLAC, ALAC, DSD, Blu-ray, SACD
HighResAudio — www.highresaudio.com
German high-res audio site offering a wide selection of music; file formats: WAV, AIFF, FLAC
iTrax — www.itrax.com
High-res audio download site that offers many recordings in either stereo or surround sound; file formats: MP3, Dolby Digital, DTS, WMA Lossless, FLAC, PCM, Blu-ray, DVD-Audio
Blue Coast Records — www.bluecoastrecords.com
Record label specializing in high-res recordings of primarily acoustic music; file formats: DSD, PCM, WAV
Channel Classics — www.channelclassics.com
Record label specializing in classical music recordings; file formats: FLAC, DSD
If there's a particular song or album you'd like to purchase as a high-res or CD-quality file, here are two search engines you can try:
Find HD Music high-res audio search — www.findhdmusic.com
FLACme CD-quality search — flacme.com
A media player for audiophiles
When it comes to storing, organizing, and playing back music on your computer, iTunes® gets a lot of things right. But it may not be the best choice if you want to build a high-res music collection. It doesn't provide the best sound quality available, and doesn't support some common high-res file formats, like FLAC.
JRiver Media Center is a popular and great-sounding alternative. It's available for PC and Mac®, and can be downloaded here.
Find the right high-res gear for your needs
You can choose from an expanding variety of high-res-capable playback equipment. Everything from portable players and plug-in digital-to-analog converters (DACs) for your laptop, to full-sized component DACs and music servers.
Still have questions? Read our high-resolution audio Q & A .