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An introduction to Mackie HM-4, based on information from the maker and distributors: what it does, how to use it and who it may suit. It is not scored.
When you need more monitoring capacity, the Mackie HM-4 four-channel headphone amplifier has you covered.
— Mackie official site
What is HM-4?
The HM-4 is a four-channel headphone amplifier from Mackie. It takes a single stereo source and distributes it to up to four pairs of headphones, so you can think of it as a headphone splitter with its own amplification.
Mackie suggests it for home studios where several people need to monitor, for distributing cue mixes to a band or vocalist, and for recording round-table podcasts.
Each output has its own level control so each listener can set a comfortable volume. Power comes from an included 12 V AC adapter.
The same HM series also includes the 12-output HM-400 and the 16-output HM-800, which are the comparison points if you need more outputs. The HM-4 is the smallest model for small groups.
One stereo source to four headphones
A single stereo source is shared with up to four pairs of headphones, enough for a small band or a few people in a booth.
Individual level control
Each of the four outputs has its own level control so every player can set their own volume.
Included 12 V AC adapter
A 12 V AC adapter is included so you can start straight away, though it needs to sit near an outlet.
Rugged build
Mackie describes the construction as 'Built-Like-A-Tank', which may suit studio and rehearsal-room use.
Versatile use cases
Mackie lists uses from demoing a mix in the studio to monitoring a round-table podcast and feeding a band in a practice space.
Step-up models
If you need more outputs, the HM-400 (12) and HM-800 (16) are in the same series. Counting how many people will monitor helps choose.
Specifications
| Item | Details |
|---|---|
| Headphone outputs | 4 |
| Input | 1/4-inch TRS (L/R) |
| Outputs | 4 x 1/4-inch TRS |
| Power | 12 V AC adapter (included) |
| Level control | Individual per output |
What is included and system requirements
- HM-4 unit
- 12 V AC adapter
- Owner's manual (also downloadable from the official site)
How to use it
- Place the HM-4 on a stable surface or in a rack.
- Connect the included AC adapter.
- Connect the stereo output of your mixer or interface to the HM-4 input with a 1/4-inch TRS cable.
- Plug headphones into the four outputs.
- Start with all level knobs turned down.
- Play audio and raise each knob to a comfortable level.
- Turn the levels down before plugging or unplugging headphones.
Band tracking monitors
When everyone needs the same mix, one unit may provide four outputs.
Podcast recording
Connect headphones for each guest so everyone hears the same signal.
Collaborative home studio sessions
Several people could check a mix, or a director could listen alongside a vocalist.
Rehearsal spaces
A band may be able to practice quietly with everyone hearing the same source.
Who it may suit
- People who want up to four listeners on one source
- People whose interface has too few headphone outputs
- People who want to add monitoring for a band or guests easily
- People who need a simple splitter for a small setup
Good to know before you buy
- There is one stereo input, so each output carries the same mix; separate mixes require another system.
- The official page's stock status may show 'On Backorder'.
- Plugging headphones in with the level raised can produce a loud sound.
- The official page lists owner's manuals in English and German.
How it differs from similar products
We do not pick a winner; the official figures are placed side by side.
Mackie HM-400 / HM-800
Mackie's comparison table lists 4 outputs for the HM-4, 12 for the HM-400 and 16 (16 x 1/4-inch TRS) for the HM-800.
Price
Please check the official page for the price.
Sources: mackie.com (checked 2026-10-27)
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