For many people, portable audio devices such as MP3 players and handheld gaming devices just don’t deliver enough oomph. We’re talking volume, people! If you’re in that crowd, give the Boostaroo Revolution an audition.
But first, make sure your headphones are a good match. The manufacturer tells us the amp is recommended for “high-end” headphones rated at between 60 and 300 ohms impedance. But we know plenty of high-end headphones that have much lower impedance ratings, including the $300 Shure E4g earphones reviewed on this page. Those units are rated at 29 ohms, and when we paired them with the Revolution, the overdriven earphones produced a lot of distortion.
When we connected the tiny amp to headphones that did fall within the recommended range, it sounded great, delivering a boost in volume ranging from pleasant to intolerable, despite being powered by just two AAAA batteries. And if you enjoy sharing your music with a close companion, the Revolution will drive two pairs of headphones by splitting the incoming stereo signal into two discrete stereo signals and delivering them to separate 1/8-inch outputs.
Oddly enough, there’s no on/off switch—plugging in the input cable turns the amp on even if the other end of the cable isn’t plugged into anything (a red LED glows to remind you it’s on). Audio purists, meanwhile, will be put off by the manner in which the Revolution reprocesses stereo signals into pseudo surround-sound to widen the sound field, a feature you cannot turn off. If neither of those characteristics bother you, and your headphones have the correct impedance, the Revolution is a worthwhile purchase. --Michael Brown