Professional Monitoring Headphones. When you need to do serious work without bothering anyone in your living space and without being distracted by outside sound, choose PreSonus® HD9 headphones. They're clean-sounding, extra-comfortable, and offer a broad, transparent frequency response that ensures accurate mixing. The HD9’s closed-back acoustic design provides superior listening isolation and reduces headphone bleed, so you hear nothing but music—and your housemates hear nothing at all. The HD9's 45 mm dynamic, neodymium drivers and high power handling (900 mW per channel into 40 ohms) deliver loud, clear, clean audio, minimizing listening fatigue. Best of all, its tailored frequency response extends all the way from 10 Hz to 26 kHz, with accurate bass response, enabling precise mixes. The lightweight HD9 features an adjustable headband, cups that rotate 180° on two axes, and comfortable, durable ear pads. The straight, ten-foot cable drops down one side so it doesn’t get in your way. The result is a comfortable listening experience that you’ll continue to enjoy during long sessions. And the HD9 is built tough so you can rely on it wherever your travels take you.