We weren’t surprised that the “U” in Yamaha’s NX-U10 portable speaker system stands for “USB,” but we were taken aback to discover that these tiny speakers can tap a USB port for power as well as digital audio.

The NX-U10’s digital-to-analog converter sounds much better than the craptastic DACs found in most laptop PCs, but you’ll enjoy a much better listening experience if you power the tiny speakers with four AAA batteries or the provided AC-over-USB adapter instead of relying solely on USB. A USB port delivers very little electrical power to the amp, which resulted in low volume levels in our listening tests.

We connected the diminutive speaker to both USB and analog audio output (the 1/8-inch stereo connector renders the system MP3-player friendly) and were surprised by how tight it all sounded. Yamaha developed a new means of reproducing bass for the NX-U10 that delivers a surprising degree of oomph from such a small cabinet (its dimensions are 9 3/4 inches wide, 3 15/16 inches high, and 1 5/16 inches deep). Dubbed Swing Radiator Bass, it consists of two panel-shaped diaphragms mounted next to the 1.5-inch drivers. Low frequencies cause these panels to swing back and forth, boosting bass response.

You’ll never mistake the bass emanating from these wee speakers for a subwoofer, or even a conventional full-range driver, but at least it’s tight. The main drivers, meanwhile, fulfill their mission with aplomb. But don’t push the amp too hard: We experienced unpleasant distortion long before reaching the end of the volume wheel’s range. Yamaha’s $180 suggested retail price, however, simply defies logic. We found the NX-U10 selling online in the more sensible price range of $96 to $108.

Drawing power from your USB port is a nice touch, but if you choose to go that route you'll forgo volume.

Yamaha NX-U10 Speakers
www.yamaha.com

Newton's Apple

Can draw power from USB; tight sound, good bass.

Olivia Newton-John

Distortion at high levels; USB power can limit volume; pricy.