High-Resolution Audio Versus Portability

high-resolution music phone
High-resolution audio is portable, but the large file sizes mean you can't take as many songs along. Innocenti / Cultura / Getty

Portability is the name of the game when it comes to listening to music and other audio content on the road. Radio represents the ultimate in portability, although physical media like cassettes and CDs also saw great success due to the easily portable nature of those formats, and digital music is even more portable, with devices like the iPod being capable of holding thousands of tracks. The recent surge in popularity of high-resolution audio has swung the needle in the opposite direction, raising the question of whether portability—or file size—is really more important than quality, or if it’s actually the other way around.

Why is Portability So Important in Car Audio?

When you look at the history of car audio, much of it seems to have been driven by convenience. Radio was the very first car audio source, and it remains popular to this day, largely due to how convenient it is. Radio allows motorists to listen to a wide variety of content without lugging around any physical media, and developments over the years have led to ever-increasing audio fidelity over the broadcast airwaves.

Pioneers in the field of car audio tried to broaden the listening choices early on, with experimental in-car photographs, and some OEMs even tested those waters, but records ultimately just weren’t portable enough. It wasn’t until an easily portable audio format, the 8 track, came into play that motorists were finally able to carry around a personal selection of music.

Then came cassette tapes, which were smaller and easier to carry around, and then CDs, which could hold more music and were higher in quality.

Finally, the ultimate in portability arrived in the form of digital music files like MP3s, which could be burned to CDs—often holding ten times more music than an audio CD—and MP3 players like iPods that could hold thousands of songs in about the same amount of physical space taken up by a single cassette tape.

What is a Lossy Audio Format?

In order to make audio content more portable, audio fidelity is usually the first thing to go. Audiophiles have long lamented the switch from analog formats like records to digital formats like CDs, but the move to MP3s took things a step further.

Virtually all of the commonly used digital music formats rely on “lossy” compression techniques, which means that at least some portion of the audio profile of the original recording is lost. Some of that is necessarily going to be outside the normal range of human hearing, but a trained ear can usually tell the difference between lossy so-called “CD quality” digital audio, like the content available for the original iPod, and an uncompressed file.

What is High-Resolution Audio?

High-resolution, or high-definition, audio isn’t a term with an exact definition, but it does generally refer to digital music files that have better-than-CD quality audio. According to Crutchfield, the typical MP3 you download from iTunes or Amazon has a bit rate of 256 kbps, while a 24-bit/96kHz high-resolution audio file has a bit-rate of over 4,000 kbps or nearly four times that of CD audio.

There are two main types of high-resolution audio files that you can purchase: uncompressed files and files that have been compressed with a lossless codec. The most common uncompressed audio files include PCM, WAV, and Apple’s AIFF. The two most common lossless-compressed file types are FLAC, which can’t be played via iTunes or Apple devices like iPods and iPhones, and Apple’s ALAC that can be played on Apple devices.

High-Resolution Audio Vs. Portability

There are a few issues with high-resolution audio, including price and the question of whether the average listener can tell the difference between lossless and lossy compression. However, the main issue in terms of high-resolution audio and mobility—whether that be car audio or simply listening to music on a portable music player—is portability.

One of the greatest strengths of lossy formats like MP3 and AAC is portability, which helped drive the adoption of MP3 players like iPods in the first place. According to Consumer Reports, you can fit about 76 tracks in one gigabyte of storage space, assuming that the songs are an average of four minutes in length and that they are compressed using a typical lossy codec.

In comparison, you can fit 27 CD-quality WAV files in that same amount of space, seven FLAC files, or just five AIFF files.

Digital storage space isn’t as big a deal as it used to be. The first generation iPod, for instance, was available with a maximum of 10 GB of storage. At the time, the iPod was advertised as allowing you to carry around 1,000 songs, due to the lower quality audio files in use at the time. Using Consumer Report’s numbers for modern audio files, that amount of space would still hold over 700 AAC files, but it would only be able to hold about 50 high-resolution AIFF files.

Of course, today you can buy an iPod with 128 GB of storage, which is enough space to hold about 640 uncompressed, high-resolution AIFF files. In real terms of how much music you can fit on the device, that’s more or less in line with the first generation iPod classic and the lower quality files that were available at that time.

When you leave the Apple ecosystem, things open up even more. For instance, Neil Young’s PonoPlayer was launched with 64 GB of internal storage and included a microSD card slot that was capable of accepting 128 GB cards. And in terms of car audio, which doesn’t have to be quite so portable as products like the iPod and PonoPlayer, a 2 TB SSD  is capable of storing upwards of 10,000 high-resolution audio files in less physical space than a cassette tape.

At What Price Portability

Although high-resolution audio is plenty portable for use in car audio, the price tag is necessarily going to be higher—and sometimes much higher—than lower quality lossy formats. Not only do high-resolution music files cost more in the first place, but the playback and storage devices are also more expensive. For instance, you can use your iPhone to listen to music in your car for very little out of pocket cost, and no cost at all if your head unit already has an auxiliary input, and portability isn’t an issue since you’re already carrying the phone around.

In comparison, listening to high-resolution audio in your car will typically involve an extra purchase—assuming you don’t already have a device that is capable of playing high-resolution files—and while digital storage space is cheap, it still isn’t free. A high-resolution audio device can run you anywhere from $100 to $300 or more, and a 128 GB microSD card—capable of holding about 600 or so songs—costs somewhere in the neighborhood of $30 to $50.

On the other end of the scale, car audio devices designed to play high-resolution audio are much more costly, and a big 2 TB SSD could easily cost in excess of $500. This is definitely a viable option, for those willing to spend the money, especially when building an in-vehicle media server, but it's still a hefty price tag.

Available storage space on portable devices will invariably go up, while costs come down, but the question of portability versus quality in car audio will remain.