Headphone monitoring set contains one headphone amplifier and four headphones. HP4: 4-channel headphone amplifier. Input/Output: 4 screaming-loud (150 mW per channel) stereo 6,3 mm jack headphone outputs (front panel). 2 balanced 6,3 mm line outputs (monitor outputs). 2 balanced 6,3 mm line inputs. Meters, Controls, and Features: Headphone level control for each channel. Mono summing switch for each channel. Monitor level control. Monitor mute switch. Daisy-chain multiple units via monitor outputs. Compact 1/3U rack-mount chassis. Sealed, detented, metal rotary controls. External 16 VAC power supply. Max Input Level: +18 dBu. Input Impedance: 10 kOhm. Frequency Response: 20 Hz - 20 kHz. Max Output Level: +18 dBu. Output Impedance: 51 Ohm. Frequency Response: 20 Hz - 20 kHz. Headphone outputs: Frequency Response: 20 Hz - 20 kHz. Headphone impedance: 32 Ohm - 600 Ohm. Dimensions: 44,45 x 139,7 x 139,7 mm. Weight: 2,27 kg. Colour: Blue. HD9: Professional monitoring headphones. The HD9’s closed-back acoustic design provides superior listening isolation and reduces headphone bleed. 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. HD9’s is combination of comfort, adjustability, sturdy construction, and acoustic isolation. Impedance: 40 Ohm. SPL: 96 dB. Cable: 3,5 mm jack and 6,3 mm adapter, 3 m. Colour: Black