With most home audio systems and portable players giving crisp quality sound using digital audio, we are no longer satisfied with the flat, bland analog sound from older car audio systems.

So let's take a look at MP3/WMA-compatible car stereos; what functions make life a whole lot easier, what features to look for in design and how to integrate them with your other in-vehicle media systems.

MP3/WMA-Compatible Car Stereo

If you normally store your digital music files on CD, a compatible stereo or changer is a good option. Up to 10 hours of music [250 songs] can be stored on a single disc and allows use of random shuffling and repeat options. This disadvantage is ease of use, having to load and unload from cassettes located in the boot or under seats, and the limited file formats that your stereo can play back. [ MP3 and WMA, some supporting AAC and ATRAC3plus formats.]

Digital Car Audio Features

The feature set of a digital system is a bit different from an analog system, largely due to the much larger music selection to manage. The following features make music selection and management a lot easier, and that means a lot safer.

Search Functions

Intuitive file navigation is VERY important able to jump quickly between files and folders. Some stereos offer rotary knobs that allow you to spin [jog] through titles quickly, while others use buttons. Some more advanced stereos even feature voice confirmation of the title of each folder, album, or song as you scroll through.

Display

Look for easily readable displays that show file and track names as well as artist and album information. These are stereos that support CD and MP3 text information [ID3 tags]) with multiple lines of display text. Car stereos with in-dash monitors obviously offer the best display capabilities; some with touch-screen controls. Make sure touch screens are fingerprint resistant, otherwise menus get easily obscured, especially in bright light environments.

File Format Support

Ensure the stereo supports common music file format: MP3, WMA, AAC, ATRAC3plus, etc. NOTE: most car stereos will NOT play back the protected music files purchased from online stores like iTunes and Napster.

Sound Shaping Controls

Compressed digital audio is "lossy" [results in the omission of certain audio information deemed unimportant or inaudible]. Sound-shaping capabilities of your in-dash stereo is important in extracting the best sound from your files. Basic Car CD Players offer tone shaping; bass and treble controls. Other features to look for include:

BBE MP and similar processing tools to reshape compressed files
loudness for fuller sound at low volumes
bass boost or a bass enhancer for giving depth to low end performance
multi-band equalizers for precision fine-tuning

Portable MP3 Player

With the popularity of portable MP3 players, the car stereo market has reacted offering connection options to connect your player to your car audio system. There are a number of ways to do this:

Interface Adapter: a brand-specific connection adapter compatible with your portable player, connects your player to car speakers and allows playback control direct from the car radio. If the car unit supports text display, track and artist information will show up, and playlist navigation is possible. See: Adapters for the Apple iPod and PlaysForSure™ for other portable players.

Aux-In: If your car stereo has an aux-in jack; use a cable between your portable player headphone or line-out jack to the car stereo auxiliary input jack. NOTE: The car stereo may require an adapter to activate the Aux-In. Control playback from the radio is not possible, but you can enjoy the best possible sound.

Bluetooth® Wireless Adapter: Using Bluetooth technology to stream files directly into your stereo via a wireless digital connection. Not able to control playback from the stereo, but the sound quality is as good as a wired Aux-In connection, but more convenient.

Wired FM Modulator: If your stereo doesn't have an Aux-In, an FM modulator can be installed between your factory antenna and your radio. This allows you to listen to music on your MP3 player by tuning your radio to a specific frequency. Sound quality isn't as good as a full wired connection.

Wireless FM Modulator: Use a wireless FM modulator to connect a portable player to your FM radio doesn’t provide the best sound quality, but is convenient.

Cassette Adapter: If your car audio system has a cassette player, you can use a cassette adapter to connect to your mpe3 player. Don’t expect great sound quality though.

Comparing Options To Connect Portable Media

Removable Media

USB sticks and SD memory cards may not offer as much storage space as a portable players, but they are the easiest way to move music from one place to another.

USB Input

Many car stereos are coming out with USB inputs, either on the faceplate or mounted to the back of the stereo. If you have a thumb drive, a front-mounted input is an easy way to listen on the road. All you have to do is connect the drive, select the song you want, and go. Most USB connections will even recognize file information and ID3 tags, allowing you to scroll through song titles and artist names as you would on your computer. You can also use the USB input to connect a compatible portable player.

Memory Card Input

Some brand name stereos now include direct inputs for a variety of memory card formats (SD card, Compact Flash, Memory Stick, etc) which allow you to send music files, images, and other information directly to the stereo. If you're going this route, make sure your radio can handle the memory card format that you're using.

HD Audio Stereo

Stereos with built-in hard drives are a growing option for digital music in a vehicle. They can be either part of an auto navigation system or audio receiver.

Advantages are the direct access, with using an integrated portable player.

Disadvantages are that using an installed hard drive stereo limits where you can listen to the music.

Loading MP3 and WMA music can be done via memory card, CD-Rom, MP3 player, or some brands let you connect the stereo [or just the faceplate] directly to your computer via USB.

Look for units that let you rip CDs quickly and easy to use file navigation features.