The most worthwhile investment you can make in improving the sound quality of your MP3 player is to upgrade the stock earbuds that came with it to a decent set of in-ear headphones. For testing the audio quality of MP3 players, we use a pair of Shure SE310 earphones shown here, which are a little pricey but sound fantastic. For around $100, you can score a set of Ultimate Ears Super.fi 3 or Shure SE110 earphones. There's also some great choices for under $50 that will blow those iPod earbuds out of the water.
A good set of in-ear headphones will also provide a nice, sound-isolating seal in the ear, reducing hearing damage caused by external noise and allowing you to listen to music at a lower volume.
Anyone who's ever tried listening to their MP3 player on a bus or the subway can attest to the fact that noise can ruin music, as well as cause you to crank the volume to unsafe levels. Active noise-canceling headphones such as the Bose QuietComfort 3s are a marvel of the modern age. Even if you work in relatively quiet office, noise-canceling headphones provide the kind of sonic solitude that can rescue your sanity and set an ideal stage for your music. While the Bose are probably the best in class for noise-canceling headphones, there are plenty of other, less expensive, options to consider.
The world may be in love with Apple's line of iPod MP3 players, but if you really want an MP3 player that will squeeze the best from your music, you'll need to tread outside of Apple's small, comfortable universe. Several manufacturers have earned a deserved reputation for outshining the iPod's sound performance, including Creative, Cowon, Samsung, Toshiba, and Sony. The Sony NWZ-A818 Walkman shown here is one of the best-sounding MP3 players of 2007.
Think that budget PC in front of you was engineered for great sound? Think again. The cut-rate audio card components used in most PCs were engineered for the lowest common denominator. If you really want to go hog-wild, you can outfit your home computer with a top-of-the-line internal PCI sound card with surround sound, S/PDIF output--the works. If you're listening to music at work, however, your boss might not appreciate you cracking open the company computer to improve its sound quality. In that case, a discreet external USB sound card such as the Creative Xmod is just the ticket.
You can't swing a fish these days with hitting some new budget iPod speaker system. Most of these things are just overpriced boomboxes, but a few of them are outstanding. The Logitech Pure-Fi Elite tops CNET's list of primo iPod speaker docks.
Why not simply patch your iPod to your home stereo using a $10 patch cable? A decent iPod speaker dock will not only offer a more convenient size than a full-blown music system, but by drawing audio from the iPod's dock connection, you'll get a cleaner signal that hasn't been colored by the iPod's puny internal headphone amplifier.
Have some old tapes or LPs that you want to transfer to MP3 files? There's plenty of ways to make quick and dirty analog-to-digital transfers, but if you want to do it right, you need to invest in a program such as Cakewalk Pyro. Using a high-quality tool like Pyro will let you splice, transition, trim, enhance, and batch-export your recordings like a pro.
For most people, upgrading their iPod's earbuds is about all the improvement they need when it comes to tackling audio quality. For those of you who refuse to accept anything but the best, however, you'll want a first-class pair of earphones, and a portable headphone amplifier that can do them justice. The HeadRoom BitHead amp isn't meant to be pretty or slim, it's just meant to provide clean and uncompromising audio performance for portable audio players. Currently priced at around $150, it might be more expensive than your MP3 player, but the BitHead's dual-use as a USB soundcard for your computer makes it a justifiable value for demanding users.
If you peek under the hood of your favorite jukebox software (iTunes, Windows Media Player, WinAmp), you'll find a treasure chest of settings that can help adjust and improve the sound quality of your music. For instance, did you know iTunes includes a 10-band equalizer, a sound enhancer control, and settings for gapless album playback?
If you're ripping music from CDs, you can increase the bit rate of your rips from the default 128kbps setting to 192kbps, or above. If file size is not a concern, then by all means rip your music to a lossless format such as WMA-Lossless, Apple Lossless, or FLAC.