Available in glossy black or white models, the 15.3-by-15.8-by-6.2-inch Sub has an interesting shape with a little window (the acoustic slot) through the middle of its body. It almost resembles a blocky, display font version of the letter O. The size is similar to plenty of subs we see, but the look is more design piece than eyesore, making its PC tower-like footprint a little easier to accept. There are very few markings of any kind on the speaker. The front panel has the Sonos logo, and the left panel houses a status light and Join button for joining a wireless network. Internally, the Sub employs two class-D amplifiers that power dual force-canceling drivers, positioned face to face. The Sub can dip down to 25Hz, and its highest crossover frequency is 110Hz. You'll want to make sure that at least one face of the Sub isn't too close to a wall or otherwise obstructed—the ported acoustic slot needs to breathe in order for efficient driver performance. The speaker can also be place...
-- pcmag.com