All of this is great, but the little Cowon really earns its keep when it comes to sound quality. At first, the experience may be a little underwhelming. The bundled earbuds are really quite nasty, producing the sort of sibilant, treble heavy noise that makes you think the iPod buds aren't really that bad after all. On the default EQ setting the player sounds weedy, and when you try to change it you discover the S9 actually suffers from a surfeit of sound modes, offering a grand total of 26 presets plus four user EQ and environmental settings at a rough count. Several of these relate to the unit's employment of the BBE+ sound processing technology, and while it's clear that these enhance the sound, it's not always clear exactly how or what they'll do without giving them a try.
On the other hand, this makes the S9 a real EQ fiddler's delight, and with a little experimentation and a good set of earbuds like the Denons I usually use for reference, it's not too hard to get a great sound. And when I say great, I mean great. The S9 can do superb clarity, making complex, heavily orchestrated music work, but it can also do warmth and depth of tone, not to mention an awful lot of bass. The Act 1 prelude from Wagner's Tristan and Isolde frightens many MP3 players, but through the S9 with suitable settings it sounds vibrant, rich and clear. The big beats in Stronger, from Kanye West's Graduation, sound tight and beefy, the vocals and synths layering over the top with just the right sense of urgency.
You can push the bass a bit too far if you pick the wrong EQ, but get it right and you can have a powerful bottom end without sacrificing mid-range warmth or high-end detail. Use Sex on Fire from Kings of Leon's Only by the Night proved that the S9 could also handle something rockier, the rhythm section propelling the track forward with a solid throb, while the waves of guitar build and crash dramatically above. Clarity and body are in perfect balance, and if you don't quite find the sound works for the track in question, there's always something you can do to fix it.