It’s no exaggeration to say that Apple has defined how people listen to music in the 21st century. Already commanding 75% of the digital music player market, the iPod phenomenon just keeps growing. In the digital-player arena, the iPod is like the New York Yankees — millions cheered when the Boston Red Sox won the World Series last year just because it was cool to see someone else take home a trophy for a change.

The problem with being on top is that there’s nowhere to go but down. And there are always rivals who would love to give you a push. Apple is far from the only maker of digital audio players, and several competitors are fielding iPod “killers” — players that promise more features for your buck (sound quality almost always depends more on the audio compression format, bit rates, and earbuds used than the player itself). We hand-picked four of the latest digital tough guys and lined them up for a throwdown with each model in Apple’s iPosse. But will they prove to be a crack team of assassins or a suicide squad?