As these are special earphones, they are not sold through normal channels. On the other hand, this is also a set of universal IEMs priced at the custom-made levels. Most IEM’s have at best two drive units. The K3003 has a dynamic bass driver that sits just outside the ear, with two-armatures for treble and midrange.
AKG custom makes the K3003 in its Austrian factory, tests every model (rather than batch testing) and comes in two versions; the K3003 (headphone only), and K3003i (headphone with in-line microphone). With the bass sitting at the tragus of the ear, the IEM extends further out of the ear than most, so styling is important. The brushed stainless steel exterior, which extends to the elegant microphone and volume control block (on the K3003i only) and even the jack socket sleeve.
Fitted with the grey-banded ‘reference sound’ filter as standard, the K3003 also includes a black-banded ‘bass boost’ and white-banded ‘high boost’ filter modules that screw onto the in-ear section of the IEM. In reality, the ‘bass boost’ is effectively a partial low-pass filter (cutting midrange and high frequencies) and the ‘high boost’ is a partial high-pass filter (cutting midrange and bass frequencies. Because of the depth of the armature and filter set, standard IEM ear sleeves will not fit in the K3003, AKG provides special latex-free spherical sleeves, in small, medium and large fittings.
Although naturally the audio output of the K3003 is compatible with almost any player or smartphone, the optional remote/microphone block of the K3003i is compatible with Apple’s 2nd Generation and beyond iPod Touch, 3rd Generation and beyond iPod Shuffle, 4th and beyond Generation iPod Nano, 120GB iPod Classic, as well as all iPads and iPhone 3GS and later versions (ensure the software of the iDevice is up to date).
The K3003/K3003i is supplied in a cigar box-sized multi-layer case. The top layer contains the headphones, the leather travel case, the filter modules and the serial number of the headphones. The second layer holds the audio adapter mini-jack socket, the in-flight adaptor, a box of ear sleeves and the manual. The travel case is designed to wrap the earphone cable without tangling – AKG studied portable use and found many people wind the earphone cable around the device when not in use, which can lay the minijack open to damage; by supplying a travel case, the user is more likely to wind the cable around this than the portable device (in theory) and thereby lengthen the mean time between repair of the K3003.
A conventional three-way loudspeaker generally has a significant advantage over loudspeakers with just a woofer and a tweeter. That middle-range loudspeaker drive unit covers the part where most music (and, for that matter, voices) happens. This is not something that is normally a function of an in-ear device, because of the lack of space in the ear itself, but the results are exceptional, at least if the K3003 is indicative of the breed.
The K3003 works from the midrange out. The clarity of the midrange is exceptional. Not just exceptional for an IEM… just exceptional, in the way something like a Stax is exceptional. There is a level of insight into the midrange that gets into the back-story of the music playing. This can be a double-edged sword; listening deep into the mix sometimes reveals details in the recording that usually remain buried, and some of them should stay that way.
That midband clarity extends out to the treble and bass, but where this works so well is the lucid way sounds appear coherent. A musical instrument extends out of that midrange without changing tonality or character. This is more a property of planar magnetic or electrostatic headphones rather than IEMs, so this is a true indicator of quality. It’s also makes voices sound uncannily accurate, although female voices are very slightly less distinct than male voices.
There’s one mild downside to the whole three-way speaker system. Because the bass unit is effectively outside the ear, the isolation properties of the K3003 are at best fair. The Tube has the oldest sections of underground railway in the world… and as a consequence it’s also one of the noisiest. Travelling around that service is a major test of an IEM’s isolation. The K3003 managed to keep a lot of the regular mid-band rumble and clanking at bay, but the top end screech of metal-on-metal between Edgware Road and Paddington stations and the general bass thump-thump-thump (admittedly hard to cut) have been better attenuated with deeper-seated in-canal IEMs.