AKG charges a hefty £379.99 for the AKG K840 KL headphones on its own website, though you can actually pick them up from online stores such as Amazon for around £250. Visit Group test: what are the best headphones?
Like the Sennheiser RS 170s, the K840 KLs use the Kleer wireless technology to provide lossless, CD-quality streaming audio. This will have obvious appeal to audiophiles, who want to get the best possible quality from their headphones.
The disadvantage of this technology is that it requires an additional plug-in transmitter to stream music to the headphones. Fortunately, the transmitter provided by AKG is small and light, and uses a standard audio jack to plug into the headphone socket on an iPhone, iPad or any other type of mobile music player, personal computer or even an ordinary CD player.
You might not want to carry the transmitter around with you if you’re listening to some music at the gym or on the tube to work in the morning, but there’s an audio cable included so you can use them as ordinary wired headphones if you want.
However, the K840 KLs are really aimed at travellers. As well as a hard-shell carrying case AKG includes a flight adaptor, along with mains adaptors for several different countries. So if you’re on a long flight you can just unpack your travel kit, and then lie back and enjoy the undeniably impressive sound quality. The K840 KL produces a deep, warm bass sound and clear, ringing higher frequencies, unmatched by any of the Bluetooth headphones in this group.
They’re expensive, and the need for the separate Kleer transmitter will put many people off. However, the audio quality provided by the Kleer technology gives the K840 KL headphones a definite edge over less expensive Bluetooth models.