Powered High-Fidelity Headphones with Built-In Audiophile Amp. Mix-Fi combines a built-in custom audiophile amplifier and insanely great-sounding drivers for a true high-fidelity listening experience. With a revolutionary, personalized fit, premium 50mm drivers and a perfectly matched amplifier, Mix-Fi delivers the most accurate yet inspiring sound you've ever heard. It's like having the power and quality of a hi-fi system inside your headphones. Features include:; High-powered audiophile amplifier custom-designed for Mix-Fi; Multi-jointed headband for superior comfort and performance; 50mm fiber-reinforced ultra-responsive dynamic drivers; Powers on and off automatically when headphones are opened ; closed; Amplifier control: passive, active, and enhanced bass