Headphone Reviews

The $1,299 K3003 seems as if it were designed to be the official IEM of the one-percenters. One look at the stainless-steel earpieces tells you it’s something exclusive and different. It’s different inside, too, with two balanced armatures instead of just one. As one might expect from a $1,299 IEM, it comes with a snazzy and unique leather case, although the case is relatively bulky.

In my opinion, though, the K3003’s rich-guy touches are nowhere near as important as its interchangeable filters. These tiny filters screw on and off the ends of the earpieces easily, with no special tools required. Filters labeled “high boost” and “bass boost” are included, along with the presumably neutral filters installed at the factory. With these, you can easily tune the K3003 to suit your taste. It’s a fantastic feature I wish more IEMs included.

Silicon ear tips in four sizes, instead of the usual three, give you a better chance of getting a good fit. An inline mic and volume/play/pause control works with Apple devices. The K3003 is also available in black, but why you’d want your $1,299 IEM to look just like all the other IEMs is beyond me.

Lauren found the K3003 reasonably comfortable, and liked its “really substantial” construction. They weren’t as kind to my ears, though — I felt part of the metal housing digging into my earlobes down around where the cable connects to the earpiece.

Sonically, the K3003 ranges from good to extraordinary, depending on your taste and your choice of filter. Overall, it definitely delivers on the promise of hybrid technology, with incredibly detailed treble and upper midrange superimposed over tight, perfectly defined bass lines. I loved hearing world-class bass but also getting the K3003’s super-spacious, airy highs. It was the only one of the hybrid IEMs tested here that really got the midrange right — that generally gave me a clear, uncolored sound in which I heard no bothersome flaws. Its treble detail was superior to the others, and several notches above the B&W C5, which uses a single dynamic driver.

Lauren felt the K3003’s balance between bass and treble was about right with the factory-installed standard filter. I thought so, too — at least at first.

I noticed that the K3003 sounded a little sibilant on some material, so I decided to try the bass boost filter, because boosting bass tends to have the subjective effect of softening the treble. It worked! The only downside was, I found myself wishing for a filter that split the difference between the standard filter and the bass boost filter. On Holly Cole’s “Train Song” (from Temptation), the bass boost filter sounded nearly perfect. It allowed the K3003 to sprinkle the recording’s hyperactive percussion all around my head while capturing all the nuances of the deep, woofer-blowing acoustic bass line. In fact, it didn’t seem to boost the bass at all, just mellow out the treble a bit. The bass boost filter nicely portrayed the lush mix of Steely Dan’s “Aja,” sounding warmer although losing a touch of treble detail compared with the standard filter sound.

On Jeff Beck’s version of “Rollin’ and Tumblin’” (from You Had It Coming), though, the bass boost filter made the sound too soft; I lost some of the edge of Beck’s guitar. And when I was listening to the bass boost filter, I often wished for a little more treble presence no matter what the recording.

I thought the mids were some of the best I’ve heard from a universal-fit IEM. The level of the midrange vis-à-vis the bass and treble sounded about right to me, and all the singers I listened to sounded smooth and natural, with just an occasional and very slight emphasis in the upper mids/lower treble.

Lauren generally liked the sound of the K3003, complimenting its ability to sort out complicated, dense musical mixes. She did, however, feel that the midrange was a little underrepresented in the mix; unfortunately there wasn’t a “mid boost” filter she could use.

The mids and treble got a little more present, though, when I used my Motorola Droid Pro smartphone as the source instead of my iPod touch. That’s because the Droid has a high 75-ohm output impedance that reacts with the K3003’s rising impedance at high frequencies. This actually gave me a nicer balance with the bass boost filter, but sounded a tad harsh with the standard filter.

Measurements

Of course, the K3003’s frequency response depends on the filter you use. With the standard filter, it’s a smoother-than-usual response without the big midrange peak found in most headphones. This is probably the reason Lauren felt the mids were a little depressed. (Good ears, Lauren!)  Treble response is much less rolled-off than usual. Increasing output impedance to 75 ohms to simulate the effect of using a low-quality source device had a milder effect than with the other hybrid IEMs tested here, boosting esponse at frequencies above 2 kHz by +1 to +2 dB but not significantly affecting the bass.

The filters turned out to have a somewhat different effect than expected given the way they’re labeled. They really didn’t affect the bass. The bass boost filter actually cut treble between 5.5 and 7.5 kHz by a max of about -3.5 dB, and introduced a slight mid peak at 2.2 kHz. The high boost filter added a pretty big, +4 dB peak at 2.6 kHz; a deep (but probably barely audible because it’s so narrow) dip at 4 kHz; and a boost of +1 to +2 dB from 5.5 to 9 kHz.

Measured using the larger of the medium tips, isolation is excellent for an IEM, about -21 dB at 1 kHz, dropping down below -50 dB from 5 to 9 kHz. That’s the best isolation I can remember measuring from an IEM. (I neglected to get a distortion measurement on the K3003 but will add this ASAP.)

Impedance is low, running 8 ohms in the bass and rising to 15 ohms in the upper treble. Average sensitivity from 300 Hz to 10 kHz with a 1-watt signal at the rated 8 ohms impedance is 98.9 dB; from 300 Hz to 6 kHz, it’s 100.2 dB.

Bottom Line

I think practically anyone would enjoy the sound of the AKG K3003, and the interchangeable filters practically guarantee you’ll enjoy the sound. But $1,299 is a colossally steep price to pay for a universal-fit IEM. For that price, you can get some of the world’s finest custom-molded IEMs, with eight balanced armatures per ear to boot. I’d definitely prefer custom-molded ’phones. But I’m sure the K3003 will appeal to those who don’t want to mess with ear molds or who aren’t comfortable with the pinna-filling, deep-in-the-ear feel of custom-molded IEMs.