Mackie HM-400 4-Channel Headphone Amplifier

The Mackie HM-400 is a professional 4-channel headphone amplifier designed for multi-user monitoring applications. It provides independent control over four separate audio channels, allowing musicians, engineers, or performers to listen to different mixes simultaneously with individual level adjustments. The unit is built into a standard 1U rack-mountable chassis, making it suitable for permanent installation in various audio environments. Key features include twelve total headphone outputs, with three dedicated 1/4-inch jacks per channel. Each channel offers comprehensive controls including mute and stereo/2-channel mode switches, 2-band EQ for tone shaping, and independent output level knobs. The front panel also provides 7-segment LED metering per channel plus a main output meter for visual monitoring of signal levels. Additional connectivity includes L/R stereo main inputs and outputs, plus a front-panel auxiliary input on each channel with a balance control to blend the main and aux signals. The amplifier is particularly well-suited for recording studios, rehearsal spaces, houses of worship, and performance venues where multiple people need to monitor audio with precision. Its robust construction, following Mackie's 'Built-Like-A-Tank' philosophy, ensures reliability in demanding environments. The HM-400 simplifies complex monitoring setups by consolidating control into a single rack unit, eliminating the need for multiple standalone headphone amps and providing a clean, organised solution for group listening sessions.