2 problems in K240 vs K271s

[pedrosollero]

Hi, I´m chosing between these two models, the 240 and the 271s. first of all, I don´t know what "semi-open" and "closed-back" mean. sencondly, and perhaps trickier to say, will I need and amp of some sort for my new headphones? My audio interface is an M-audio Ozonic.
Thanks very much for the attention,
Pedro Sollero

[Karl]

Hi Pedro,

   In open type of headphones the drivers are coupled via a more or less open earpad to the ear. Advantage is that open types of headphones in most cases sound more natural then closed types. Disadvantage is that the sound insulation is very poor and the sound can substantially vary depending on the pressure of the pads to the ear. Closed types of headphones are tightly sealed to the ear. The back of the earpieces therefore is closed. They often suffer from an unnaturally emphasized bass.

Semi open headphones combine the advantages of both closed and open designs. The sound remains stable independent on the ear pressure (determined by the head size and aging effects of the earpads) and they have a fairly good sound insulation.

Especially the K271 and K171 due to a highly sophisticated acoustic design ensure a sound image that is as good as in open types of headphones but the sound insulation is excellent.

The low impedance vesion of the K240 Studio and the K271 will give a sufficiently high volume on sound cards and portable equipment without the need of a seperate amp.

Kind regards

Karl