Koss KDE250 Dual-Element Headphone (Playback 39)

Something New Under the Sun

When I first saw Koss’ unorthodox-looking KDE250 headphones ($249.99), I was reminded of the punch line to a Saturday Night Live sketch where the actors peered at strange, inscrutable objects and then blurted out, “What the h*ll is that?”

In the case of the KDE250 quizzical looks arise for several reasons. First these ‘phones don’t look quite like anything else on the market, with a design that appears to be a cross between an ultra high-tech NASA-grade earbud and some sort of communication device from sci-fi film. Second, though you realize the KDE250 is surely a headphone of some kind (hey, the logo says “Koss” on it, doesn’t it?), it’s not at first clear whether you are supposed to wear the things on your ears or in them. And as it happens, the answer to that particular puzzler is “both.”

PRODUCT CONCEPT

Koss’ KDE250 dual-element headphone provides separate, clip-on earpieces for your left and right ears and it is, as its name suggests, a dual-driver headphone of deceptively unusual configuration.

When you first look at the KDE250’s earpieces, two features catch your eyes. First, there is a moderately large, disc-shaped driver housing (for the 20mm low-frequency driver, as it happens), which is about the diameter of a quarter, but considerably thicker. Second, you’ll note that the earpiece housings incorporate futuristic-looking, satin-finished metal ear clips, fitted with cool, micrometer-type adjustment knobs that allow ultra-precise height adjustments for a comfortable fit. Finally, the earpiece frame is hinged in the middle so that you can adjust the angle of the driver assembly relative to you ears.

At this stage, one might be tempted to think, “Oh, I get it; the KDE250 is pretty much a typical on-ear headphone with a hinged frame, distinctive ear clips and cool adjustment knobs.” But while that assessment is partly true, it is also misleading, because the KDE250 offers design features that I, for one, have not seen on any other headphone. Allow me to explain.

If you turn the KDE250 earpiece over in your hand, you’ll make the startling discovery that its large disc-shaped driver housings are fully enclosed on both sides, meaning there are no apparent openings through which sound could be directed into your ears. Hunh? How could that be? Where does the sound come out?

We’re glad you asked. On the back of each main driver enclosure you’ll find an unusual appendage that protrudes at right angles from the main enclosure. Closer inspection reveals that the appendage is in fact a small, streamlined nacelle that houses the KDE250’s tiny 13mm tweeter/midrange driver, and that also provides vent ports through which the low-frequency driver delivers bass to your ears. But here’s the really unusual part. Those little driver nacelle/vent port assemblies are set up so that they fits sideways in the ear canal, radiating sound from the back toward the front of your ear canals. What is more, unlike typical in-ear headphones, the KDE250s make no attempt to form an airtight seal in your ears. On the contrary, the 250’s driver nacelle/vent port assembly fits comfortably within the ear canal yet without blocking it, so that wearers can still hear room sounds quite easily.

Why would Koss go to such lengths to create such an unconventional headphone? According to Koss President and CEO Michael J. Koss, the KDE250 is meant to provide “the ultimate in portable personal listening,” but I think the actual answer is subtler and more nuanced than that.

As near as I can tell, Koss had three objectives in mind with this product, all of which help to position it as a strong, viable alternative to traditional in-ear headphones (which, for the record, Koss also makes). First, the KDE250 strives to deliver an overall sound that is significantly different from, and in some respects superior to, the sound of typical competing in-ear ‘phones. Second, the KDE250 aims to provide a comfortable, customizable fit that deliberately overcomes the objections of listeners who dislike the tight, earplug-like feel of typical in-ear ‘phones (or who dislike the loose, imprecise fit of typical earbuds). Third, the KDE250 is targeted toward listeners who want to enjoy very high sound quality, but also need or want to hear potentially important sounds around them (e.g., phones ringing, office mates approaching to ask questions, etc.). As you’ll learn in this review, the KDE250 meets all three objectives quite successfully.

EASE OF USE

One consequence of the KDE250’s unusual design and shape is that newcomers invariably ask, “How do I put them on?”