What Is Lossless Audio, and Do You Really Need It?

There’s a difference, of course, between “putting some music on” and “listening to music.” The first is just a nice way of disturbing the silence while you get on with some task or other, while the second is a way of transporting you into a world of emotion and expression. And so it follows that while the first doesn’t require an exceptional level of quality to be effective, the second benefits no end from sounding as close to the artist’s original intentions as is possible. For digital music, that's lossless audio.

You may have heard more about lossless audio recently, thanks to a growing number of music streaming services offering it as part of their subscriptions, most recently Spotify. But what exactly is lossless audio, how do you get it, and does it really make a difference? Let's get into it.

At the risk of stating the obvious, lossless audio is digital audio that has lost none of the information originally contained in the recording. This doesn’t mean it hasn’t been compressed—both lossless and “lossy” files will have been through a process of compression in order to make sure the digital file is of manageable size to be streamed reliably. It’s the size of the file after that compression that defines whether it’s lossless or not—and there are two numbers that are relevant here.

First is the “sample rate,” which is the number of times per second the analog audio signal is examined as it’s being converted into digital information. The higher the sample rate, the more accurate the digital information should be—a compact disc has a sample rate of 44.1 kHz, for example, which means the analog signal is sampled 44,100 times per second as it’s being converted to digital.

Next, there's “bit depth,” which signifies how much of the analog sound wave each sample of the signal is capturing. The higher the number here, the more of the analog audio signal is being examined, and the more accurate the transcription of the information from analog to digital. It also helps deliver greater dynamic range, which is the distance between the quietest and the loudest moments in a recording. Compact disc uses 16-bit audio.

The 16-bit/44.1 kHz resolution that compact disc uses was acknowledged at the time of the technology’s development as the best compromise between capturing as much data as is audible to the human ear as possible and keeping digital audio files down to a manageable size. And it has endured—any digital audio file with a resolution of at least 16-bit/44.1 kHz can be described as lossless, as long as it’s stored in a lossless format like FLAC (Free Lossless Audio Codec) or, indeed, on a compact disc. Anything less than this—often expressed differently, in kbps—can safely be termed “lossy,” while anything larger takes us into the realms of “high-resolution” audio (which is ultimately anything higher than CD quality, but generally it's considered as anything with a 24-bit bit depth or above).

Short answer: yes. Information is knowledge, after all, and knowledge is power—or, in this instance, knowledge is access to as much audio information as possible, which keeps your music sounding as the artist intended.

The slightly longer answer: yes, as long as you’re using equipment capable of revealing all of the information contained in a lossless audio file, then it will sound better* than the lossy equivalent. This means everything from your source of music, how well the digital information is converted to analog, its amplification and, finally, the speakers or headphones that serve it to your ears.

(*in this instance I’m using “better” as a catch-all for “more detail,” “more dynamism,” “more convincing rhythmic expression,” and all the other specifics that go into making for a truly satisfying listening experience.)

The A&norma SR25 MKII from Astell & Kern is one of our favorite audio players.

Courtesy of Astell & Kern

You’re not short of ways to get a fix of lossless audio. Compact disc is enjoying something of a resurgence of popularity as younger listeners discover a) its very acceptable sound quality, b) its relative affordability thanks to charity shops and the like, and c) the straightforward pleasure of a physical storage format—building a collection, even—for audio content.

There are a number of download sites that offer lossless audio files as a minimum, too. You’ll pay to purchase specific audio content which can then be stored locally, on network-attached storage, or on the memory card of a digital audio player. Which means you’ll own the music, rather than renting it from a music streaming service.

Ah yes, music streaming services. Some of them, like Tidal and Qobuz, have been making access to lossless audio their whole raison d’être ever since they launched. Others have had to basically be shamed into finally delivering audio quality that’s superior to that of someone shouting into a bucket. But if you want to combine convenience with access to an extraordinary amount of lossless audio content, a top-tier subscription to a credible music streaming service will do you very nicely indeed. As well as Tidal and Qobuz, the services that currently offer lossless audio include Apple Music, Amazon Music Unlimited, Spotify, and Deezer.

The transmission of lossless audio is a chain, of course, and every link in it needs to be able to deal with lossless audio. So it's important to consider your system as a whole.

First of all you need the content, of course. Maybe it’s a CD, a downloaded digital audio file stored locally, or a lossless file cued up on the app of your favorite music streaming service. If it’s a CD, then naturally your CD player is capable of converting the lossless content from digital to analog (in order for it to make sense to your speakers or headphones and, ultimately, your ears), and the same is true of lossless content stored in the memory of a digital audio player. Then all you need is your headphones or speakers—the final link in the chain—and you're good to go.

If you have a catalogue of lossless content on a network-attached storage device, you’ll need a network streamer to do the digital-to-analog conversion business before it passes it on to an amplifier (or indeed, you can opt for something like the Wiim Amp Pro, which can do it all), and then onto your speakers.

If, like most people, you’re using a music streaming service on your phone or tablet and want to play your music through wireless headphones, then there are a few things to consider to ensure you are hearing the music in the quality you're paying for. Which brings us neatly onto the next point …

The Wiim Amp Pro is a do-it-all network amplifier that can help you stream lossless and high-res music wirelessly at home.

Photograph: Simon Lucas

Standard Bluetooth doesn't have the bandwidth to support the amount of data that's needed to transmit lossless music. Instead, it will downsample the signal into a lossy one en route to your speakers or headphones—which is annoying if you're paying a streaming service extra for the privilege of better quality music.

However, there are new Bluetooth codecs (which is the software that compresses and encodes digital audio files ready for wireless transmission, then decodes and decompresses at the other end) available hoping to improve this. Qualcomm has been behind the biggest strides forward here, and its most recent aptX Lossless promises true lossless streaming via Bluetooth. The only problem is that both the source device (your phone or tablet) and the playback device (your headphones) need to support it in order for it to work.

And this is where it gets tricky. Many top-tier Android phones support aptX, but the iPhone doesn't. That means if you want to play music losslessly from an iPhone, you will either need to use a wired USB-C to USB-C headphone connection, a portable DAC that does support aptX or, if you're at home, play your music back over Wi-Fi instead.

Yes, but once again there are exceptions to be aware of.

The easiest way to listen to lossless audio wirelessly is probably using the “Connect” versions of music streaming service apps, like Qobuz, Spotify and Tidal. These are now commonly built into a range of speakers and playback devices, allowing lossless tracks—and even hi-res music—to be streamed directly from the company's servers to a compatible device over Wi-Fi.

However, if you're an iPhone user and have been using AirPlay 2 to stream to your speakers, you probably haven't been hearing your music losslessly. While the protocol officially supports music up to 16-bit/44 kHz, it currently downsamples any lossless music to a lossy stream of 256 kbps.

Of course, if you have a NAS drive filled with lossless tracks, and a network streamer/amp and speakers, then Wi-Fi can handle all of this just fine.

There's no need to compromise on quality when you're out and about—you just need to ensure you have the right equipment to support it. That could be:

• A pair of wired headphones connected to a digital audio player loaded with some lossless content is a very straightforward way of getting your lossless audio kicks on the go.
• A pair of wired USB-C headphones, your phone, and a lossless music streaming service will also ensure your lossless tracks remain lossless.
• For wireless lossless streaming on the go, ensure you have a source device and wireless headphones that support Qualcomm's aptX Lossless Bluetooth codec.