Your MacBook’s built-in speakers are fine for the odd YouTube clip of dogs jumping in slow motion or for listening to NPR streams. But when it comes to bringing the rock to your desktop, they’re pretty weak sauce. Twelvesouth aims to improve your audio situation with its BassJump, a USB subwoofer built to boost the beats coming out of your MacBook.

Hooking up BassJump literally could not be easier. Connect it to a USB port with the included cable, and you’re done. The first time out, you’ll have to download and install the BassJump Preference pane, but once that’s done, your system will automatically recognize the subwoofer when it’s plugged in. And at less than one and a half pounds, you’ll probably be moving the 5x5x2.24-inch BassJump frequently--either between Macs or in and out of your travel bag.

But remember that BassJump is designed with MacBooks in mind. So while it provided marked improvement in the audio performance of our favorite laptop, it was less impressive when hooked up to our iMac. That’s because the iMac has more powerful speakers--a fact that, to its credit, Twelvesouth freely admits on its website. So for most of our testing, we wired up the BassJump to our 13-inch MacBook Pro, listening to everything from A Tribe Called Quest’s old-school hip-hop jams to Yeasayer’s indie electronica beats--and to good effect. The sound coming out of our MacBook went from being tinny and paper-thin to full enough to rock our office. If you do a lot of listening at your desk, the BassJump is a great alternative to the innumerable iPod speaker docks crowding the market at about the same price point.

Its Preference pane is also clever, allowing you to adjust the crossover point, fine-tuning the frequencies that get sent to the subwoofer. There’s also a separate slider to control the BassJump’s volume. Between the two settings, you can tune the system to your liking--or just use one of the five presets for different genres of music. The included padded carrying case makes BassJump attractive for travelers too. It’s hard to find fault with BassJump--it performed well with minimal fuss. We love that it grabs audio and power via a single USB connection, although a pass-through USB port would have been a nice touch since BassJump eats up one of your two precious ports.