It's been a while since we had a truly high-end pair of headphones through the office. Many might consider spending more than $100 on headphones to be overkill. But the sky is the limit for those who truly appreciate high quality audio. With a street price of just over $400 (and an RRP of more than double that!), the AKG K701 headphones are not exactly cheap; however, you definitely get what you pay for. These are one of the best pairs of reference quality headphones we've heard. They combine incredible treble with brilliant mid-range and detailed bass to create an extremely compelling product.

The first thing to note about their sound is that they aren't quite as bass heavy as some competing units, such as the Sennheiser HD600. It isn't quite as powerful or visceral as some users may be used to and it doesn't extend as deeply or decay as slowly. However, that isn't to say the bass isn't great — it really impressed us. It is tight and punchy with great detail and it is well balanced with the other elements of the sound. We found the balance more suited to styles such as jazz, acoustic and classical than rock and roll.

That said, in our rock and metal tests the headphones did a fairly solid job thanks to the brilliantly detailed mid-range. Everything was clear and distinct; you can hear the individual string plucks, even in a mass of noise. The sound gelled together well, flowing seamlessly from simple deep bass lines to thunderous guitar riffs to sweeping piano solos.

The transparency and clarity offered by these headphones really is their key selling point. It is incredible to listen to something you've only heard on an inferior setup with a high quality piece of gear like this; it's like a whole new song. We were concerned the clarity would perhaps be too revealing, which can be problematic on low quality recordings, but it wasn't an issue.

The treble reproduction is also notable. Piano-based tunes sounded incredible: The highs are rich and sweet with a smooth, liquid tone that is absolutely wonderful. This, combined with the slightly less powerful bass, gives them a somewhat bright sound, although everything is so well-balanced and flows so nicely that it's hard to note too much emphasis on one section.

As you'd expect from a top-tier product, these headphone also have a fantastic soundstage. It is extremely airy and open, which lends itself to live recordings quite nicely. They did well with whatever we threw at it and created a good level of immersion.

With a fairly hefty design, they certainly aren't portable. They are, however, quite comfortable, with huge, soft cups and a leather headband that adjusts to your head. They could be considered a little tight at times, but overall we had no issues during long listening sessions.

As with many high-end headphones, they also benefit greatly from a dedicated amplifier. While they aren't quite as demanding as some competing models (they will work with an iPod or similar source), the sound gets a noticeable boost in quality by using a separate amp, which adds to the cost if you want to make the most of your setup.