PreSonus HD9 Professional Closed-Back Monitoring HeadphonesPreSonus HD9 headphones let you do serious work without bothering others in your living space and with no outside sound distractions. They're extra comfortable and clean sounding, with a broad, transparent frequency response that ensures accurate mixing. Nothing but clear and accurate sound Their closed back acoustic design gives superior audio listening isolation and reduces headphone bleed, so you'll hear nothing but music, while your housemates