This is an amazing headphone. It was made 25-30 years ago, and is still going strong. There are 2-3 diffrent versions of this headphone with diffrences in the bass/detail. The diffrent verions can be identified by the color of the cross-over circut board and the color of the passive elements in the cup.

The thing that makes this headphone so special is the unique use of both fynamic and electrostatic drivers, along with 5 passive radiators in each cup. The dynamic drives is afull range driver that has lower level of mid and highs. The electrostat is connected to a XO board that is set at 4kHz and is a first order 6db/octave XO.

This headphone is a great headphone for every type of music that doesn't require large amounts of bass. One of the best things about this headphone is the great potential it has when modded. There are many diffrent mods that can be done (look at my current equipment in the profile and you'll see a link) that make this headphone better than most if not all the headphones in production today and cost under 1000$ or so.

The K340's are very hard to drive with a 400 ohm's impadance and a low sensitivity. But when given a proper amp (such as the DV 336i, or the Sigle-Power MPX3) it really coms allive and shines.

They were sold with pleather pads that get hot and cant keep the original size after all these years, but veloure pads can be ordered from AKG that make these headphones much more comfortable.

I had the chance of hearing many great headphones (W5000's, SR-007, SRS-3030, GS-1000 etc) but the K340's are the best once modded. The only one that can challenge them are the 007, it will depend on your personal preferences in audio.