Many people consider Audio Technica's A900s to be the premiere un-amplified headphone in the world, and with good reason. They combine comfortable build quality with solid isolation and some of the most incredible sound you will ever hear in this price bracket.

The headphpnes sport Audio Technica's trademark design. Two pads support the phones on either side of the head, with a strap above them joining the two fragments. The A900's are a closed headphone, signified by the A in the model number, and thus the Pleather cups completely encircle the ears. They are quite comfortable to wear over a short period of time, but throughout longer listening sessions in hot weather your ears can become itchy and overly warm. A quick break every hour or so remedied this for us, but it is worth noting.

The closed design means they isolate sound quite well, which helps if you're using them in an office or other quiet situation. We did get a little sound leakage from them however, which surprised us; normally closed headphones are considered primarily because of their suitability in quiet environments.

Being a closed headphone, the A900s should have a more limited soundstage than that of an open model, but we were pleasantly surprised by how three dimensional the sound was. It wasn't as good as that of the AD700 (an open model), but it offered very realistic, if a quite intimate placement of each instrument. It is not ideal for recreating a large orchestra hall, but it is a huge step up from the flat, two dimensional presentation found in a lot of models.

Sound quality was nothing short of incredible. Thanks to the closed design the A900s have a slightly slower bass sound, with stronger, more prominent low notes. Drums and synthesisers have a huge presence, giving the music a lot of force. That isn't to say they drown out the treble however. If anything, the A900s treble is its strongest element. The highs are spine-tingling, with smooth transitions and enough detail to pick out things you'd never heard before.

The one area the A900's lack in is the mid range, and it is not so much a failing as just a lack of emphasis. A lot has been made of the weaker mid range of this model, and whilst it can sound a little recessed, that is only in comparison to the stronger bass and treble elements. No headphone has it all. Overall the sound is great for someone who likes a little more bass, particularly those listening to rock or electronica, but it is also outstanding for gamers or movie watchers who want some strength given to gunshots and explosions.

One big thing to note about the A900s, the sound is probably the best you will find from an un-amplified headphone. Whilst they will benefit from a dedicated headphone amplifier, the A900s will run perfectly from a PC soundcard or even a portable device. Most of the other headphones that offer similar (or better) sound will require you to spend $500 or more on suitable amplification, making the A900 excellent value for money.