PreSonus HD9/HP4PACK Four-Person Headphone Monitoring Bundle

The PreSonus HD9/HP4PACK is a studio headphone-monitoring bundle built for sessions where up to four people need to hear the same source. It combines one HP4 four-channel headphone distribution amplifier with four HD9 closed-back monitoring headphones. This setup helps musicians, producers, podcasters, and recording guests monitor together without relying on a single headphone output.

The HP4 accepts a stereo line-level source from compatible mixers, audio interfaces, and playback devices with 1/4-inch TRS outputs. Four front-panel headphone outputs provide separately adjustable listening levels, so each user can set a comfortable volume. Rear monitor/thru outputs also allow the incoming source to feed studio monitors or another HP4.

Each included HD9 headphone uses a closed-back, circumaural design to help reduce outside distractions and minimize headphone bleed during recording. Its 45 mm dynamic neodymium drivers are designed for detailed monitoring with extended low-frequency reach. The 10 Hz to 26 kHz frequency response supports tracking, editing, and mix-reference work.

The HD9 design includes a precision-tuned acoustic chamber, 40-ohm rated impedance, and up to 900 mW of power handling per channel. Two-way earcup rotation and an adjustable headband support flexible positioning at a workstation or console. Long-lasting ear pads and a single-sided cable help keep the headphones practical for repeated studio use.

For control-room workflows, the HP4 includes a monitor-level control, monitor mute switch, and mono switch. The mono function sums the left and right input signals to both sides of the headphone and monitor outputs. Its monitor/thru outputs can also connect to another HP4 when a larger headphone-distribution setup is needed.

Key Features

• Four-Person Monitoring: Includes one HP4 amplifier and four HD9 headphones.
• Independent Headphone Levels: Each HP4 headphone output has its own volume control.
• Closed-Back HD9 Design: Helps reduce outside noise and headphone bleed.
• 45 mm Neodymium Drivers: Delivers extended-range dynamic headphone monitoring.
• Mono and Monitor Controls: Supports mono checking, monitor level adjustment, and muting.
• Monitor/Thru Outputs: Feed studio monitors or another HP4 distribution amplifier.

Design & Installation

The HP4 uses a compact desktop format with front-panel headphone jacks and level controls for direct access during sessions. The HD9 headphones use closed-back circumaural earcups, 45 mm neodymium drivers, an adjustable headband, and rotating earcups. Each HD9 has a straight, single-sided 3 m cable terminated in a 3.5 mm stereo connector.

Connect the left and right line outputs of a mixer or audio interface to the HP4's balanced 1/4-inch TRS inputs. Plug the included HD9 headphones into the four front-panel 1/4-inch headphone outputs using their supplied adapters, then set each listener's level individually. Connect the rear monitor/thru outputs to powered monitors, a power amplifier, or another HP4 as needed, and start with all volume controls turned down before raising levels.