Audio-Technica ATH-M50x Professional Monitor Headphones, White - With FiiO Kilimanjaro2 A3 Portable Headphone Amplifier (Silver) Audio Technica ATH-M50X Professional Studio Headphones FiiO A3 Portable Headphone Amplifier - Color may Vary Exceptional clarity throughout an extended frequency range, with deep, accurate bass response Proprietary 45 mm large-aperture drivers with rare earth magnets and copper-clad aluminum wire voice coils - Exceptional clarity throughout an extended frequency range, with deep, accurate bass response Critically acclaimed sonic performance praised by top audio engineers and pro audio reviewers