The CX300 headphones are of the variety that sit inside the user's ear canal, which means they're surprisingly effective at cutting out external noise. That's why this type of headphone is becoming known as a pair of 'isolating headphones'.

Although they don't do any noise-cancelling, unlike, say, Sony's MDR-NC50 headphones, these headphones form a seal inside the user's ear, like earplugs. That cuts out quite a lot of extraneous noise, which has two effects: it makes the listening experience more pleasant, and also means the player can be run at a lower volume, as there's less noise around to interfere with the music.

That, of course, is good news for long-suffering ears that have had to suffer loud music over the noise of a tube train.

Headphones such as the CX300 have another advantage – they usually have better bass response than their competitors which sit just in the user's ear. That's certainly the case with this pair, with a deep, rich bass sound that is far above most of its competitors, particularly down at this price range.

Treble sounds are also good, although they did tend to come out slightly louder than the bass in our test tracks, necessitating a bit of twiddling with the settings on the music player. Overall, though, we can't complain about the sound quality.

If you haven't used isolating headphones before, they can feel very odd in the ear – particularly as sound gets cut out from the outside world as well, leading to a little disorientation. For most people, this seems to go away fairly quickly.

Unlike the Koss Plug headphones (see below), the CX300 uses rubber rings over the earplug which create the seal in the ear. There are three pairs supplied (small, medium and large) and users are encouraged to experiment and find the right one to fit comfortably.

At £40 they're a lot more expensive than the Koss, but Amazon is currently selling both the black and silver models for £22.50, which makes the CX300 a bargain.

Related reviews 
Koss 'The Plug'
Despite the minor problem with the foam on the earphones the Koss Plug is a cheap and effective way of cutting out background noise
Rating 3/5
£15