Tension Labs EAP03 Audio Processor review: Tension Labs EAP03 Audio Processor

The Tension Labs EAP03 ($179) is a personal headphone amplifier intended for hi-fidelity audio enthusiasts looking to get the best performance from high-end in-ear headphones.

Design
Measuring 3.25 inches by 2 inches by 0.5 inch, the Tension Labs EAP03 has the look and feel of a knockoff iPod Mini constructed by the lowest bidder. Despite its metallic look, the Tension Labs EAP03 is plastic from head to toe, with a subpar build quality that doesn't match its lofty price tag.

On the front of the Tension Labs EAP03 you'll find a 1.5-inch monochrome LCD that displays volume and setting information in legible, yet crude, lettering. Below the display you'll find a built-in microphone and two clear acrylic buttons for enabling the Tension Labs EAP03's audio processing, or external noise monitoring features. The Tension Labs EAP03's doesn't include a button hold switch, however, making it all too easy for the gadget to turn on or off accidentally.

On the left edge of the Tension Labs EAP03 you'll find a single spring-loaded scroll wheel for navigating and adjusting the Tension Labs EAP03's settings. The bottom of the EAP03 includes a USB charging port and two 3.5mm stereo jacks for routing audio in and out.

Beyond the Tension Labs EAP03's aforementioned cosmetic shortcomings, there's a larger design issue to deal with here, namely: size. For what amounts to an incremental improvement in audio quality, it's cumbersome to carry around a device as large as the EAP03 along with your MP3 player. Granted, there is a small, but devoted, faction of audio enthusiasts roaming around with much bulkier headphone amplifiers, such as the HeadRoom Bithead--but that doesn't make the proposition any less ridiculous.

Features
As the two buttons on the front would indicate, the Tension Labs EAP03 has two basic functions. First and foremost, the Tension Labs EAP03 is an earphone amplifier, meant to optimize your MP3 player's performance with high-end in-ear headphones such as the Shure SE 530, or Ultimate Ears Super.fi 5. To make this audio magic happen, the Tension Labs EAP03 employs dual 24-bit Sigma Delta audio codecs on a 48-bit processor packed with detailed EQ, amplification, and spatialization settings.

Just how many gadgets are we expected to reasonably cram in our pockets, exactly? The EAP03's bulky plastic design makes us wonder if squeezing extra fidelity from our earphones is worth the effort.

The Tension Labs EAP03's second purpose is its external noise monitoring capability. By pressing the Mic button, the Tension Labs EAP03 routes the output of its internal microphone into your headphones and displays a decibel meter that can be used to gauge potential risks to your hearing. Unfortunately, this feature feels like a cure that's worse than the disease. Without a button hold switch or any way to disable headphone monitoring, our ears got a rude awakening each time the Mic button was accidentally brushed.

An internal USB-rechargeable battery powers the Tension Labs EAP03, offering 8 hours of playback. Bear in mind that the Tension Labs EAP03 cannot be used in a passive mode. If the EAP03 runs out of juice during playback, you'll need to disconnect it and plug directly into your MP3 player like the rest of the common folk.

For an asking price of $179, there are a handful of features we expected to see on the EAP03, but didn't. For instance, if Tension Labs had included controls for panning and switchable mono and stereo modes, the EAP03 would be much more appealing to folks with partial hearing loss. Considering that the EAP03 already includes an ambient noise-detecting microphone, it seems tragic that there isn't a switchable noise-cancellation feature included, as well.

Performance
To get the most from the Tension Labs EAP03, you'll need to find out the impedance of your earphones and dial in the appropriate sensitivity setting. We tested the EAP03 using a set of Shure SE310 earphones and both a fifth-generation iPod and Zune 80.

Without a doubt, the Tension Labs EAP03 provided a subtle enhancement to our MP3 player's fidelity. Although we found the included 3D sound spatialization feature horrific, using the three-band user-definable EQ offered pleasing results, enhancing sonic clarity across the board.

The overarching problem with a portable earphone amplifier is that MP3 players offer an inherently compromised listening experience. Even if you're ripping your music to lossless audio files, people typically use portable audio players under less-than-ideal circumstances, where street noise and screeching subway cars often mask musical frequencies. That's not to say that you shouldn't try to make the most of a bad situation, but at some point you have to admit that you're throwing money at a problem that can't be solved. That said, those of you using your MP3 player in quiet situations along with earphones capable of reproducing high-fidelity detail, might find value in the Tension Labs EAP03's audio enhancement.