Digital Reference Series headphones derive the maximum benefit from digital sound sources, including compact disc, DAT and MiniDisc. Aura-Nomic design corresponds to the natural angle of the ear; it eliminates excess pressure and provides more natural, more balanced sound. 50 mm diameter driver is larger than most headphones for deeper bass, lower distortion and wider dynamic range. Bio-cellulose diaphragm uses natural fiber construction for light weight and extremely high rigidity; it resists the distortions caused by diaphragm bending and flexing; produces pure, superbly natural sound. Higher-power Neodymium magnet packs 30% more energy than conventional Neodymium. Linear crystal oxygen-free copper (OFC) class 1 cord provides maximum conductivity with minimum noise. Closed earpads allow for superlative isolation from outside sounds, high effective signal-to-noise ratio. Self-adjust headband enables maximum listening comfort, hour after hour. The headphones incorporate Sony UniMatch plug system with fixed mini plug for portable use and detachable phone plug for home hi-fi use. Gold-plated plugs resist corrosion for high conductivity, low noise. A carrying case is supplied for enhanced portability.