Pop quiz: How do you find the volume of a cube?

If you said, “Multiply the length of one side by itself twice, duh!” you’re technically correct, but also wrong.

In the case of TDK’s 10-inch-by-10-inch-by-10-inch Sound Cube, here’s the answer: Locate the knob that goes to 11.

This is not a joke. This boombox’s volume control maxes out at 11 (yes, that’s a reference to This Is Spinal Tap). But all kidding aside, this sleek speaker cube puts out some serious sound.

It’s not just that the two 5.25-inch coaxial drivers really crank. Or that there’s crisp quality and separation. Or that the bass gets impressively aggressive. What the Cube does really well is: fill a room.

There are four cones, one on each side. Two of them are active drivers, and the other two are passive reflectors. With sound being pushed in every direction, you never need worry about repositioning the speaker to boost the audio.

That’s not to say you won’t be moving this thing around. Beyond the AC power supply, it also runs on D batteries. We rocked the Cube indoors and out. It’s not exactly featherweight (16.6 pounds with batteries), but the comfy leather handle made it easy to tote. There are other little details and tiny touches that make this Cube a winner: The volume knob clicks when you turn it on, just like hi-fi stereos of the ’70s and ’80s.

Aesthetics aside, the Sound Cube has more ports than the Riviera: USB (for thumb drives or iPods–iPhones), 3.5mm audio jack, and an auxiliary audio jack — wait for it — for a ¼-inch instrument cable. That’s right: The Cube doubles as a small, portable amp. Granted TDK’s “11? didn’t exactly shred our ear drums with 20 watts of total power, but hey: Do the math. Multiuse + portable + excellent sound = three bills = : )

WIRED Recharges devices connected by USB (even when it’s running on batteries). Solid battery life: We rocked for an entire weekend, including one 4-hour party, and are still going strong. Rubberized top keeps your connected iPhone from slipping in transit. Matte-black shell prevents fingerprints. Straightforward navigation + easy-to-adjust digital equalizer. Surprisingly decent AM–FM reception. 3.5mm and 30-pin iPod–iPhone cables included.

TIRED Requires 12 D batteries (12!) for portable play. Weak mix between instrument and other sources (i.e., Cube is great as an amp, but not as a Karaoke box). No remote control. Battery-cover screws can’t be removed without a coin or screwdriver. Ports located towards bottom: If you move the Cube, cables often get caught underneath.

Top photo: Jim Merithew/Wired.com. Bottom photo courtesy TDK.