Overview
The Mackie HM-400 is a rack-mountable, 4-channel headphone amplifier designed to provide versatile headphone amplification for artists, musicians, and engineers. 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. 

Features 

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.The HM-400 ships with an IEC power cable and occupies 1 RU in a standard 19 "rack.

-        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 "per unit input

-        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

-        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 and mute St / 2-Ch (stereo / mono) mode

-        7-segment LED metering for input and each output channel

-        Heavy-gauge steel chassis for rugged durability

Specifications

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 & quot; 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 & quot; 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 & quot; / 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 "

What's In The Box

-       HM-400

-       Power Cable