Sennheiser advertises the HD 229 as having a "Deep Bass Kick", suggesting that they're bass-centric headphones like most of their more eye-catching counterparts such as the Skullcandy Lowrider. However, in truth their sound is much more easily defined by its bright, detailed treble and overall warmth.
There is bass here, but it's not a dominant feature. For the most part, we consider this a good thing, as there's not a hint of boominess to the HD 229. The low-end could extend deeper, though, and those attracted by the claims of bass on its packaging may be disappointed. These earphones actually have a sound among the most delicate of on-ear pairs in their sub-£80 class.
The Sennheiser HD 229 excel in providing plenty of top-end detail without introducing harshness - to an extent that's impressive for under £100, regardless of earphone/headphone type. This light and insightful sound brings the best results when in a fairly quiet place. The ear pads provide some noise isolation, but not as much as a set of IEMs or an over-ears pair, and the thoughtful sound loses some of its impact when dealing with the intrusion of ambient noise. We took them out for a test drive on tubes and trains on a few occasions, and they cope well enough - but they only shine under less external strain.
These headphones are rather mis-sold, but we can honestly say we prefer their sound to that of most colourful and loud-looking sets. You may feel differently, however. They offer little of the bombast of the Monster Beats, and if you want that sort of power, the Sennheiser HD 202 are a better buy.
Sennheiser has rather shot itself in the foot in making the HD 229 look quite as much like their sobre-suited cousins, the HD 228. We were unable to find the HD 229 for under £59.99 - limiting the search to reputable retailers, naturally. The HD 228, on the other hand, can be found for as little as £30, and offer pretty-much identical sound and build - as well as a classier look, in our humble opinion. The 229's may be good headphones, but their sound sign signature is likely not what you might expect, and the price hike for the sake of 'style' doesn't convince us.
Sennheiser's HD 229 on-ear headphones sound rather different from the norm of brash-looking sets. While they claim to offer a "Deep Bass Kick", they are actually rather bright and detailed, with a low-end that's relatively reserved and well-behaved. This earns them a few audio pedant points, but makes us feel that they're not all that well matched with their intended audience. And when the very similar HD 228 can be snagged for around half the price, their decent performance isn't enough to earn them our recommendation.