The Westone UM2 earphones are little larger to fit in the second driver, which makes all the difference in the world to the sound.

The case, tips, cable, coding-coding - almost everything about the UM2s is the same as the UM1s, except for their size and price. The dual drivers make the earpieces nearly twice the size and three times the cost of the UM1s. The tips also go into your ears at more of an angle than the UM1s, though not as sharp an angle as the Shure E500s. We found that this made them easier to fit and less likely to slip than the UM1s.

The other difference is the sound. The noise isolation of the UM2s is as good as the UM1s but the audio quality is definitely better - although again, this is very dependent on getting the right fit and seal in your ear for the bass and detail, and it requires a touch more volume than the Shure E500s, for example. These are a good comparison with the Shure E500s, in fact; dual instead of triple drivers mean the price of the UM2s is around three quarters what you'd pay for the Shures, and the sound quality does reflect that, but not by a great deal. The Shure E500s are of a similar size, although reflections on the metallic surface make them look smaller even though they have triple drivers.

Like the UM1s, the UM2s tend to have a slightly neutral sound; there's no lack of bass or response, but there's no added punch or coloration in the music either. Detail is exceptional with clear, clean overtones, which make piano and percussion sounds natural and very impressive. Bass is rich and defined, although the UM2s will highlight any flaws in recordings (as well as low bitrate MP3s). The loss of treble in the UM1s isn't a problem for the UM2s. Midtones are strong and sound separation is good; you're close to the sounds, but they're placed around you rather than inside your head. Overall, the sound is both rich and clean.

At this price you'd expect more accessories with the UM2s, though. You'll probably find that only one of the two sizes gives you a good fit, which means that you've effectively only got one spare pair of tips. There is no adapter for larger headphone sockets, no volume attenuator, no rubber or flanged tips to experiment with, and no adapter for airplanes. What you get is excellent headphones with no frills. (Note that custom tips are available for the UM2s as well, if you want to invest the necessary time and money.)