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Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer — main product image
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer
Behringer

Behringer Micromix MX400 Ultra Low-Noise 4-Channel Line Mixer

★★★★★4.3 (2327 reviews)

Four channels of 4580 op-amp headroom in a palm-sized box — the MX400 cleans up line-level submix duties without adding noise to your chain.

$52.76*
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*Price sourced from Amazon.com. Last updated:Jun 19, 2026.Price and availability are subject to change.

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Overview

The Behringer Micromix MX400 is a four-channel line mixer built around NJM4580 operational amplifiers — a dual op-amp IC with a long track record in audio applications for its low noise and low distortion characteristics at line-level voltages. Each of the four channels accepts a 1/4" TS input with a minimum impedance of 4.7 kOhms and provides an individual level control before summing. The output stage presents 80 ohms impedance and handles up to +16 dBu, which covers the dynamic range requirements of synthesizers, drum machines, outboard effects, and consumer audio sources. The 16 dB noise specification is measured at the output — at line level, this translates to a signal-to-noise ratio that keeps the MX400's own noise contribution inaudible in all but the most clinical studio monitoring environments.

In practice, the MX400 fills a specific and common gap: you have four line-level sources that need to reach one destination. Keyboard rigs feeding a single channel of a front-of-house console, multiple software synth outputs merging to a single interface input, effects units returning to a single aux channel — these are the sessions this unit is built for. The unbalanced 1/4" TS architecture is a constraint in balanced professional environments, but for the studio musician or live keyboardist working with consumer and prosumer gear, it is a non-issue. At its physical size and price point, the MX400 is a utility device, not a centerpiece — but a utility device built on a circuit that doesn't add audible color or noise to the sources running through it.

Key Features

Ultra-compact 4-channel line mixer

Highest sonic quality even at maximum output level

Input Level control for each channel

Ultra low-noise 4580 operational amplifiers for outstanding audio performance

DC 12-Volt adapter included

Specifications

Number of Channels
4
Input Connectors
1/4" TS (unbalanced)
Input Impedance
Min. 4.7 kOhms
Max Input Level
+16 dBu
Output Connector
1/4" TS (unbalanced)
Output Impedance
80 Ohms
Noise Level
16 dB
Op-Amp
4580
Power Supply
12V DC adapter (included)

Pros & Cons

👍 Pros

  • NJM4580 op-amps deliver a measurably low noise floor at line-level operation, keeping submix contributions transparent in a larger signal chain.
  • Maximum input level of +16 dBu provides sufficient headroom for hot synthesizer and drum machine outputs without clipping.
  • Per-channel level controls allow independent gain staging of four sources before the summed output — essential for balancing disparate signal levels.
  • 80-ohm output impedance drives long cable runs and most mixer aux inputs without degradation.
  • Compact form factor fits on a desktop, in a rack drawer, or zip-tied to a keyboard stand without consuming meaningful real estate.

👎 Cons

  • All connections are unbalanced 1/4" TS — integration with balanced professional gear requires additional adapters and introduces potential ground loop risk.
  • No master output level control; total output level is determined only by the sum of the four individual channel faders, making overall gain management less precise.
  • 12V DC power supply is wall-wart only — no battery option and no USB power, which limits truly portable applications.
  • Input impedance of 4.7 kOhms is adequate but not generous — passive high-impedance sources may experience subtle loading.
  • No EQ, aux sends, or inserts — what you see is what you get; it is a pure summing device with no signal shaping capability.

Frequently Asked Questions

The specified noise level is 16 dB, and the 4580 op-amps maintain low noise at unity gain — but understand this is a line mixer, not a mic preamp. It is operating on signals already at line level (+4 dBu or -10 dBV), so the noise contribution is well below audible threshold under normal use. Pushing all four channels to maximum output simultaneously is where you'll start to see the headroom ceiling at +16 dBu.
All inputs and the output use 1/4" TS (unbalanced) connectors. The output impedance is 80 ohms, which is appropriate for driving most mixer aux inputs and line-level destinations. If your downstream gear is balanced (XLR or TRS), you'll need a DI box or passive adapter — the MX400 does not provide balanced outputs natively.
No. The MX400 is a line-level device with a 1/4" TS output designed for feeding another mixer or recording interface. It has no headphone amplifier stage and no dedicated headphone output — driving headphones directly from the TS output will produce low volume and potentially poor frequency response.
Minimum 4.7 kOhms per input. That's sufficient for synthesizers, drum machines, effects units, and consumer line sources, but it's on the lower end — some high-output passive sources may see slight loading. Active line sources (keyboard outputs, DI outs) will drive it without issue.
No phantom power is involved — this is a line mixer only. It runs on a 12V DC power adapter, which is included in the box. It does not operate on USB power or batteries.

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