Sleek Audio SA6
Everyone's ear canals have unique shapes that affect hearing; some of us pick up high frequencies better, while others are attuned to bass. These in-ear headphones are the first that let you tweak the acoustics to suit your ears—or your taste—avoiding the distortion that results from adjusting the equalizer on your music player. For more thump on hip-hop tracks, attach the bass modules to the back of each earphone, adding larger chambers for the sound to resonate. Make vocals stand out by changing the treble filter on the earpiece to one that allows more high frequencies through. $250; sleek-audio.com
And they're so thrifty!
$250 for a small plate to increase bass and a filter for treble is mighty steep. In my opinion, there isn't justification for an earbud headphone to be over $40. It's a small full range driver attached to light gauge wire.