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.
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
Packaging Info
Package Weight 10.5 lb
Box Dimensions (LxWxH) 20.8 x 10.6 x 4.1"