AKG K 601 Reference Class Stereo Headphones are premium reference headphones are for anyone who appreciates true high-end equipment. These future-oriented, open-back dynamic headphones not only offer good wearing comfort but they also deliver an incredibly detailed, full, yet crisp sound. This is the result of a new AKG Varimotion two-layer diaphragm that ensures optimum diaphragm motion for extremely accurate highfrequency response and a powerful low end.