Headphone Reviews

To most people, the only apparent differences among in-ear monitors (IEMs) are the logos on the sides. But there are two very different technologies used in IEMs.

The most common one, the dynamic driver, is a miniaturized version of a conventional speaker. It’s best known for powerful bass. The other one is the balanced armature, which is like a miniature teeter-totter that moves a diaphragm to make sound. It’s best known for extended, detailed treble.

A few manufacturers have recently tried to get the best of both worlds by combining a dynamic driver and a balanced armature (or two or more) in a single, hybrid IEM. I’ve had a few hybrids kicking around for a while and decided to review all three together.

The models are Audiofly’s $209 AF78, Scosche’s $249 IEM856md, and AKG’s ultra-high-end, $1,299 K3003.

These are among the few universal-fit hybrid IEMs available in the U.S. There are also several custom-molded hybrid IEMs on the market, such as Unique Melody’s Merlin.

I listened to all three at length on my own, then called in L.A. voice actress Lauren Dragan to give me her impressions. Lauren spends lots of her life wearing headphones, and she’s sampled countless models during our tests — and best of all, her opinion sometimes doesn’t square with mine, so you get two experienced listeners for the same price as one!

As a reference headphone, Lauren relied on the same set of Sony professional over-ear headphones she uses for her gigs. I used the B&W C5, which is the closest thing I’ve found to a universally loved IEM. She used an iPhone to drive the headphones; I used an iPod touch and a Motorola Droid Pro.

After our listening, I ran all the IEMs through my measurement setup: a G.R.A.S. Type RA0045 ear simulator, a Clio FW audio analyzer, and a Musical Fidelity V-Can headphone amplifier. I inserted and reinserted each tip several times, and settled on a position for each that gave the most representative result.

Before we go any further, let me get one thing on the record: While we can generalize about the sound of dynamic drivers vs. balanced armatures, there are no hard-and-fast rules. I’ve heard dynamics with good treble and balanced armatures with potent bass.

And let me add that this isn’t a “shootout,” it’s just a survey of what’s out there for hybrid IEMs at the moment. ’Cause do you seriously think anyone’s going to be choosing between a $250 IEM and a $1,299 IEM? That’d be like narrowing your choice of car down to a Toyota Yaris or a BMW 750i.