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.
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.