PreSonus HD9/HP4PACK Four-Person Headphone Monitoring Bundle 15 Inch Subwoofers The woofers use waterproof polypropylene

The woofers use waterproof polypropylene cones with thermoplastic-elastomer surrounds

7 dB sensitivity rating and 34

8 wideband speech support is designed to improve call clarity

Polypropylene Cone: Provides the woofer's primary sound-producing diaphragm

7-inch length can simplify placement in installations with limited mounting room

PreSonus HD9/HP4PACK Four-Person Headphone Monitoring Bundle 15 Inch Subwoofers The woofers use waterproof polypropyleneThe 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,