There are many things to consider when choosing a digital audio player, from the audio formats it plays to its expansion options and the software it uses. Understanding the importance of these features is key now that there are so many players on the market at ever more affordable prices. This buying guide will help you make an informed choice when it comes to purchasing your digital audio player.

Digital Audio Hardware: Benefits and Drawbacks

Digital audio players have several things going in their favour including their small size, but most people buy them for their ability to play songs from any album in any order they choose. Gone are the days of lugging your entire CD collection around on trips--with digital audio players you can download your favourite tracks from multiple albums to the player and create your own greatest-hits album. Best of all, you can reuse the player's memory, adding and removing songs from your player as often as you like.

Most of the digital audio hardware on the market is solid state, meaning that it has no moving parts. This makes the units more durable and eliminates skipping (something that owners of older portable CD-player know of only too well). However, there are exceptions to this as there are digital audio players that store files on hard drives, CD-R and CD-RW media and even MiniDisc.

A stumbling block for many solid state digital audio players is their limited storage capacity. A digital audio player with 32 MB internal memory will store around one hour of music encoded using MP3 audio compression and about 40 per cent more using the WMA format. A 64 MB player offers twice the amount. This is something to think about when buying a player especially if you're planning on taking it on holiday. However, digital audio files can be encoded at various bit rates, enabling you to store more music per MB but at a cost--the lower the bit rate, the lower the audio quality. It is now becoming increasingly difficult to find solid state players with less than 128 MB memory. A recent development in solid state players is the ability to use them as portable hard drives. When the players are connected to a personal computer, the PC thinks that the device is an extra hard drive, allowing you to store other files on the device.

Digital Audio Formats

MP3, or Moving Pictures Expert Group Audio Layer 3 to call it by its proper name, is a digital audio format that is "encoded" on a personal computer or dedicated recorder from an audio source such as CD. The encoded files are compressed into far smaller sizes while retaining near-original sound quality, making it easy to download songs from the Internet or store music collections on your computer's hard drive. MP3 has become a generic term for digital audio players, but in fact, many can play different formats of compressed audio such as WAV, WMA and of course MP3.

While the MP3 format has become an international standard, other digital audio formats are growing in popularity. The best digital audio players are capable of playing back many formats of digital audio such as WAV, WMA and AAC. A popular alternative to MP3, Microsoft's WMA format can compress files into even smaller sizes while retaining audio quality. If you're worried about future audio formats, don't be. Many players are firmware upgradeable so they can play formats that have yet to be invented. Players able to handle only MP3 files aren't necessarily a bad deal and can save you some money if you don't want all the extra playback capabilities.

Memory and Recording Capacity

Digital audio files are stored in the player's internal memory, so the more memory you have, the more music you can carry along with you. You can generally expect to store about one hour of standard MP3 music on 32 MB storage. But this does depend on the bit rate used when the files were originally encoded. Do remember that you can sacrifice audio quality to gain more storage space.

When looking at players, be sure to see if the amount of memory listed in the specifications is actually built in to the device or exists in the form of a memory card that can be swapped out. Solid state players have a pre-determined amount of storage space, normally 32 MB, 64 MB, 128 MB or 256 MB, although most of them offer some sort of expandability through additional memory packs or memory cards. Swappable memory cards theoretically offer infinite expandability, limited only by your budget. However, note that some digital audio players will accept cards up to a specific size. A device with integrated memory and no memory expansion slots isn't as versatile but many of the players with integrated memory also have memory slots so you get the best of both worlds.

Mass Storage

Players that use hard drives for storage are generally more expensive than players that rely on solid state memory, but they make up for this by offering hundreds of megabytes (or even several gigabytes) of storage. The more expensive units in this category, such as the Creative Labs Jukebox Zen can store over 500 hours of music, and some will even allow you to record straight on to the unit.

Hard drives deliver excellent storage capacity for the money but unfortunately they use moving parts and are therefore more fragile than devices that use solid-state memory. It's a good idea to use a carrying case for a portable digital audio player with a hard drive, ideally one with a shock-resistant case.

Hybrid Digital Audio Players

Manufacturers are constantly looking for newer and more exciting ways of delivering digital audio to the consumer and the current trend is for hybrid CD/digital audio players. These players combine a standard portable CD player with digital audio playback capabilities. Simply insert a CD-R or CD-RW full of MP3 files into the unit and away you go. You can store about 10 CDs worth of MP3 on one 80-minute CD-R--ideal for those wanting to take lots of music with them on holiday while still being able to play audio CDs. Hybrid players work in exactly the same way as conventional portable CD players, although instead of taking the CD out to change album, you simply select a different folder from an on-screen menu.

Sony has gone one stage further even though it also has hybrid CD/digital audio players on the market. It's taken their popular and highly trendy MiniDisc format and made it possible to download and play digital audio files on a MiniDisc unit. Sony's new Net MD players can record from various sources, accept multiple Internet audio formats, such as MP3 and WMA files.

MP3 on DVD

One feature turning up on a lot of home DVD players is the ability to play MP3 files stored on CD-R/RW discs. Players automatically recognise a disc containing MP3 files and play them accordingly. Some players offer different audio controls such as bass boost and treble control. MP3 playback is great on a DVD player if it is connected to an external amplifier and speaker setup.

PDAs Play Digital Audio

It's not only specific digital audio players that can play music on the move, many of the newer PDAs can happily play both MP3 and WMA formats. All you need to add is a set of headphones, with a connector that links to the audio output on your PDA, typically a 3.5 mm jack. Do be aware that devices such as the Handspring Visor require an additional plug-in module to play MP3s. PDAs that run either Microsoft Windows for Pocket PC or Microsoft Windows for Handheld PC have the ability to play both MP3 and WMA files, because the OS includes a version of Media Player. The Palm OS based Sony Clié range of PDAs also offer digital audio playback--the Sony Clié PEG-NR70V features a built-in audio player and includes all the necessary software and hardware needed to enjoy music on the go.

Displays and Labelling

Most digital audio players have displays that can show all sorts of information about the track that's playing, including the title, artist and length. At the very least, try to find a unit with a backlit LCD that can be read easily at night. High-end units support detailed labels such as ID3 tags (small pieces of data--such as song title, artist and album title--that can be added to a digital audio file when it is created via encoding software), while some just show the track number and length.

Software

Good bundled software adds much value to a player, but be aware that plenty of MP3 utility programs are available separately. The best software will let you make your own playlists, mix tracks from several different sources into a compilation album. Many programs, including MusicMatch MP3 Jukebox Deluxe, integrate directly with CDDB, a vast database of album names, track titles, and artists that can automate all your labelling chores.

The software included with digital audio players also lets you "rip" and encode songs from other formats, most commonly CDs. Ripping is the act of copying digital data directly from the CD, and encoding is the process of converting that data to the MP3 format. The software you use will dictate the quality of your recordings, so it's important to use a high-quality package.

Interfaces and Transfer Rates

One of the sad facts of digital audio players is that you have to transfer music to them from a computer or other source. Early players used a serial port interface for these file transfers, an agonisingly slow way of trying to fill a 32 MB or larger memory capacity. All digital audio players on coming out now use a USB interface which can send data to the player at up to 12 megabits per second. That's theoretically fast enough to fill a 64 MB memory card in less than a minute.

Extra and Advanced Features

As the digital audio market heats up, manufacturers are adding more and more features to their devices to distinguish them from the pack. Some players have a built-in tuner for listening to FM radio broadcasts. Some have voice-recording capabilities and even a digital camera. If the devices you are comparing have advanced features like this, read as many reviews as possible to see if the manufacturers actually made the features useful. For example an FM tuner looses much of its charm if station presets are left out of the equation.

Equaliser Presets and Bass Boost

Since digital audio of all types is compressed, there is a minor compromise to sound quality, so finding a player with equaliser controls or other features for enhancing the sound can add to your listening experience. Managed badly, it can also make the sound considerably worse. Some players come with several equaliser presets, such as jazz, pop and rock. Or check out players with user, or custom, settings, which will allow you to establish personal equaliser levels. There are also units with a setting that artificially expands the bass frequencies, eg: bass boost technology.

Accessories

Be mindful of included accessories when comparing digital audio player prices. You can save a lot of money if you don't have to buy things like AC adapters, cigarette lighter adapters and headphones separately. Few players come with carrying cases but as most digital audio hardware has no moving parts, it generally can take more abuse than something like a portable CD player.

Compatibility

Before buying a digital audio player, make sure it's compatible with your computer. All the players we've seen work with PCs, but not all of them work with Macs. Also note that just because your computer has the requisite hardware to interface with the player doesn't mean it will support the software that the player needs to work. For instance, PCs with a USB port must use Windows 95 (OSR2) or later in order to take advantage of it. In addition, Windows NT 4.0 does not have built-in operating system support for USB connectivity, though there are third-party solutions available for working around this. Your computer needs to meet (or preferably exceed) the system requirements listed on the box to guarantee compatibility with all the player's components. Also, just because you've got the latest OS for your computer it doesn't automatically make all digital audio players compatible with your hardware. Windows XP users may have trouble with some hardware so check the technical data and system requirements of a player before you invest.

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