The Mackie HM-400 is a rack-mountable, 4-channel headphone amplifier designed to provide versatile headphone amplification for artists, musicians, and engineers monitoring through headphones in live stage applications and home, project, commercial, and mobile-recording studios. It features a stereo main output via XLR and 1/4" jacks and twelve 1/4" TRS stereo headphone outputs—three per channel—fed by a customizable blend of inputs.


One stereo main input via XLR and 1/4" jacks can be mixed with a per-channel 1/4" stereo aux input. Each channel offers 2-band EQ for quick tone shaping, stereo balance or main/aux input mix control, and output level adjustments. Also on each channel are switches for muting left and/or right signals and operating in stereo or mono. 7-segment LED meters display main input and per-channel output levels.

MPN: HM-400
UPC: 663961054088

• Distribute signal to up to twelve pairs of headphones
  
• Occupies 1 RU
  
• One stereo main input via XLR or 1/4" jacks
  
• One 1/4" stereo aux input per channel
  
• One stereo main output via XLR or 1/4" jacks
  
• Three 1/4" headphone outputs—one on the front panel and two on the rear—per channel fed by an output level control
  
• 2-band EQ per channel for quick treble and bass adjustments
  
• Per-channel Balance knob allows control of left/right level balance or aux/main input mix
  
• Switches on each channel for L/R mute and St/2-Ch (stereo/mono) mode
  
• 7-segment LED metering for input and each output channel
  
• Heavy-gauge steel chassis for rugged durability
  
  
• XLR & 1/4" Stereo Inputs and Outputs
  
• Three Headphone Outputs per Channel
  
• Per-Channel 1/4" Stereo Aux Input
  
• 2-Band EQ, Balance, and Output Controls
  
• L/R Mute Switches
  
• Stereo/Mono Mode Switches
  
• LED Metering
  
• Includes Power Cable
  
  
• Number of Channels 4
  
• Input Connections 2 x XLR 3-pin balanced (one stereo pair)
  
• 2 x 1/4" TRS balanced (one stereo pair, also accepts 1/4" TS unbalanced)
  
• 1 x 1/4" TRS stereo unbalanced for main input
  
• 4 x 1/4" TRS stereo unbalanced for aux inputs
  
• Output Connectors 2 x XLR 3-pin balanced (one stereo pair)
  
• 2 x 1/4" TRS balanced (one stereo pair, also accepts 1/4" TS unbalanced)
  
• 12 x 1/4" TRS stereo unbalanced headphone outputs
  
• Maximum Input Level: Main Input: +15 dBu
  
• Aux Input: +20 dBu
  
• Maximum Output Level: Headphone Outputs: 550 mW per channel at 47 Ohms (+21 dBu)
  
• Input Impedance: Main Input: 20 kOhms balanced, 10 kOhms unbalanced
  
• Aux Input: 10 kOhms unbalanced
  
• Output Impedance Headphone Outputs: 3 Ohms unbalanced
  
• Gain Range: Main Input: -66 to +18 dBu
  
• Function Controls: Power on/off
  
• Main level knob
  
• L/R mute switches per channel
  
• Stereo/2-Ch switches per channel
  
• 2-band EQ per channel
  
• Balance knob per channel
  
• Output knob per channel
  
• Frequency Response: 20 Hz to 20 kHz (±1 dB)
  
• THD <0.01% (+4 dBu, 1 kHz, unity gain)
  
• Noise: -66 dB
  
• CMRR: Main Input: >42 dB at 1 kHz
  
• Display: 1 x input level meter
  
• 4 x output level meters
  
• Power Requirement: 100 to 120 VAC, 50/60 Hz, 24 W
  220 to 240 VAC, 50/60 Hz, 24 W
  
• Power Connector: 1 x 3-pin IEC male, 250 VAC, 10 A
  
• Construction Material: Heavy-gauge steel chassis
  
• Dimensions (H x W x D): 1.8 x 19.0 x 8.8" / 46 x 483 x 224 mm
  
• Weight: 8 lb / 3.6 kg