Sony's MDR-AS40EX earphones cost a manageable $40 and are perfect for use in the gym or jogging. But their suitability in this regard does not translate into excellent sound performance overall. The MDR-AS40EX lacks tremendous bass; even the $20 TuneBuds from Griffin best these earphones in the low-frequency output department. Still, bass isn't everything: You do get clear, crisp audio, and the included fit kit ensures that the 'phones stay put. What's more, unlike some other in-ear models, the MDR-AS40EX has almost no cable microphonic issues ("cable thump"), especially when used with the included shirt clip. Even so, I prefer the fit and sound of Sennheiser's superb workout earphones, the MX75 Sport. Although the MDR-AS40EX costs about $25 less than the Sennheisers, you get what you pay for.

In appearance, the MDR-AS40EX is fairly nondescript: A thin black cable and silver stems lead to black eartips, and there's a bit of metallic red at the top of each earpiece. The included circular carrying case is made of black plastic and is a bit big for my taste—approximately 3.8 by 3.6 by 1.2 inches. The included fitting options—three different rubber eartips and over-the-ear "hangers"—should leave no earpiece loose. Personally, though, I found the hangers a bit awkward. A shirt clip is provided on the cable, as well as an extension cable. (The standard cable is quite short in case you keep the player in a shirt pocket or secured close to your head.)

The aforementioned Griffin TuneBuds are cheaply made and not my favorite, but they do offer slightly more low end than the MDR-AS40EX. But not everyone is a bass addict—in fact, some people hate extra low end. For the listeners in that camp, this Sony pair should suffice as a workout earphone set. I noticed distortion only rarely at high volumes, and generally speaking, it handled the low end well. There's no boom, but the lack of bass saves the MDR-AS40EX from getting fuzzy at high volumes. I occasionally found them too bright or crisp on rock vocals and guitars, but not to the point where it annoyed me. The kick drum in Nirvana's In Utero lacked some of the low-end thud I'm used to hearing on those recordings, but the vocals and guitars sounded excellent.

I'm not in love with the Sony MDR-AS40EX, but if $40 is your limit, then you have few decent options. My cranky advice is to save up and buy a better pair—for instance, almost anything from Sennheiser at the $60-and-up level. But the MDR-AS40EX from Sony will stay in place, won't hamper your listening with overpowering "cable thump," and—considering the price—delivers acceptable audio quality.

Compare the headphones mentioned above side by side.