Just about everything you need to know abut the MDR-XB500's is in the XB of the model number. XB equals extra bass, and tells you that the MDR-XB500s are part of Sony's recently launched range of headphones and earphones aimed specifically at delivering a more powerful bass sound than the more general purpose MDR-EX and MDR-XD ranges.
In fact, Sony claims that it analysed sound across all types of music to create drivers specially tuned for R&B, hip-hop and dub. To give you some idea, the XB500 specifications list a frequency range of 4 to 24,000Khz, and while I'd take such figures with, let's say, a good truck-full of salt, there's no question that the XB500s go very, very deep and very, very low.
And I mean it. Give the Sony's something like Massive Attack's Inertia Creeps to work with and you don't quite so much listen to the music as feel it, every big beat and low bass note hitting you like an earthquake going off somewhere deep below your feet. Oddly, it's not a bad experience in any way. The bass isn't harsh or excessive or booming; in fact it's actually quite smooth and well controlled. It's just that it's there in a way you probably haven't heard it before, and it does dominate the rest of the audio spectrum.
It's not that the XB500s can't deliver any sort of detail at the high end, it's more that top-end clarity, definition and sparkle isn't really its thing. These are headphones designed to produce great results from a few musical genres, and the rest can pretty much go hang.
When they're good, the XB500s can be very good. Some headphone aficionados will talk of headphones that replicate the ‘in the studio' sound or the live band sound or the concert hall sound, and the XB500s do something similar: recreating the sound of a really good club.
The big 40mm Neodymium drivers probably help, as does an acoustic design aimed at channelling the bass signal straight into your ear. Sure, there's not a lot of room for fine detail at the top end, but what you do get is big, warm and deeply immersive - as long as you play the right music.
DJ Shadow's Fixed Income, for example, gives you a pretty good idea of how rich and atmospheric the XB500s can go. The beats sound huge; the bass-heavy textures beneath the guitar parts are impossibly thick and yet beautifully defined. Other headphones might capture the weird harpsichord sounds with more fidelity, but not many headphones under £100 will give you the track with this kind of atmosphere.