Everyone knows the iconic image of the DJ — the permanently worn headphones, satchel full of vinyl, twin Technics 1200 turntables — but that could all be about to change with iPod Battle Tokyo: The Clash this Friday, where nine DJ teams will fight it out using nothing but a pair of slimline, portable hard disks connected to a mixer.

There was never any impediment to DJs connecting their iPods to a regular mixer, and since the device's birth in 2001, DJs have been using their iPods in conjunction with CDs and vinyl, simply for convenience's sake. Some might sneer at the poorer sound quality that still afflicts digital music, and obviously vinyl purists need not apply, but judging from the number of DJs who perform directly off their laptops, there are plenty who don't share these reservations.

Despite seeming largely useless to professional DJs due to the inability of the iPod to do beat-matching (altering the tempo of one song to mix smoothly with another) and other such staples of the DJ's art, the last couple of years have seen iPod DJ nights becoming more and more popular, as well as the appearance of dedicated iPod mixers such as the Ion/Numark iDJ, the KAM I-MIX100 and the Phonic Mixpod (none of which are yet widely available in Japan, although an import iDJ retails for about ¥19,000 at Yodobashi Camera). Since an iPod is basically just a hard disk, effects such as pitch-shifting and scratching can in theory be added by the mixer itself, which should also negate the need for two iPods. A common criticism of the iDJ and Mixpod is that they don't offer either of these, although the I-MIX100 brought in pitch- control and Numark's iDJ2, recently released abroad, allows the simultaneous play of two tracks off the same iPod.