AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm

AUDIOPHONICS MPA-M400ET Amplificateur Mono Class D Purifi 1x400W 4 Ohm
Class D mono power amplifier based on a PURIFI 1ET400A module and a HYPEX SMPS600A400 power supply.

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Shipping date: 02-12-2022.

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Accessories for this product

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Power amplifier PURIFI 1x400W 4 Ohm

We are proud to present AUDIOPHONICS MPA-M400ET, a class D mono power amplifier based a PURIFI 1ET400A module. This ready-to-use version is designed for audiophiles needing a foolproof amplification solution, with a considerable power reserve as well as impeccable linearity. The PURIFI module is indeed among the most rigorous Class D amplification solutions on the market, with simply exceptional measured performance.

This device offers high level sound reproduction which will be suitable to drive demanding speakers, to sonorize large listening rooms or for studio applications requiring a considerable headroom without compromising on the precision and richness of the audio message.

All of the components are integrated in a sober and robust 100% Aluminum housing with openings and heatsinks to help heat dissipation. Its design also allows it to block signal interference.

Module PURIFI 1ET400A

  • The amplification circuit uses its own PURIFI 1ET400A module. This high performance Class D amplifier circuits offers a very comfortable power of 200W (@ 8Ω) while making the most of Class D amplifiers high efficiency rating.
  • The 1ET400A module has a >75dB high gain loop over the entire frequency band, providing high performance across the whole spectrum and surpassing any amplifier regardless of its class.
  • Thanks to hyper-low intermodulation distorsion (IMD) the MPA-M400ET achieves incredible precision over the whole spectrum, unmatched by audio amplifiers of any technology or operating class.
  • THD remains extremely low at any frequency and any power level right until clipping. This translates into a total lack of sonic signature, and an ability to reproduce any type of music without preference for genre or production style.
  • The output noise is negligible, which allows deep silences and prevents losing details when listening at low volume.
  • The circuit benefits from a high level of rejection (PSRR) which minimizes the impact of power supply on audio performance.
  • Load-invariant frequency response and negligible output impedance enables the MPA-M400ET to drive the most demanding speakers with ease.
  • Very low idle losses and reduced electromagnetic interference (EMI). The High loop gain allows relaxed timing of the power MOSFETs without degrading audio performance.
  • The MPA-M400ET interfaces its amplifier module with a custom module specially developed for its optimal integration.

Power Module Hypex HYPEX SMPS600N400

SMPS600N400 switching power supply is a model with very high maximum output power of 600 Watts. It has been specifically designed and developed by Hypex to provide 2 x 65V voltage required for operation of the most demanding amplifier modules.
This low noise high quality Power supply, meets every energy needs of the amplification modules. Furthermore, the amplifier modules themselves have an excellent ability to reject power supply noise. The MPA-M400ET has lowest sensitivity to the variations of your electrical network  liable to cause parasitic noise.

Audiophonics Interface Card

The amplifier module Purifi is driven by a controller module of our design. 

A Texas Instrument LM4562 OPA per channel is used, these are very low distortion AOPs offering the greatest transparency with a very low THD. They are mounted on socket allowing their replacement if necessary

To suit all uses we opted for 3 gain settings, adjustable by jumper on the interface card :

  • Gain of + 7.2dB, for a total of 20dB (default) - Maximum power reached with a signal of ~ 4.2V RMS
  • Gain of + 12.5dB, for a total of 25.3dB - Maximum power reached with a signal of ~ 2.2V RMS
  • Bypass: in this case the signal passes directly from the inputs to the modules, allowing the lowest possible gain of 12.8dB. This mode can be interesting when using a powerful preamplifier, capable of driving a load of 2 to 4kOhm and reaching a voltage of ~ 10V RMS


Designed for easy integration, the MPA-M400ET has a balanced mono (XLR) and unbalanced mono (RCA) input. A bipolar selector make it easy to change the input source and even allow independent channel control when paired to another MPA.

Output side, BP-209 terminal blocks Ø5.5mm acrylic / 24K gold insulated terminal blocks ensure an excellent connection with the speakers and supporting bare cables (5.4mm), banana plugs and spades.


The MPA-M400 ET has a 5-12V trigger input integrated in a low consumption circuit (5ma). Your amplifier blocks can thus easily reach your High Fidelity installations with remote power on control.


Frequency response

THD vs Freq

TypePower Amplifier
Output power (max)8Ω @1%THD : 227W
4Ω @1%THD : 425W
2Ω @1%THD : 450W
THD+NPO=1W, f=1kHz 0.0007 %
PO=10W, f=1kHz 0.00026 %
PO=100W, f=1kHz 0.00015 %
PO=1W, f=20-20kHz 0.0007 %
PO=10W, f=20-20kHz 0.00029 %
PO=100W, f=20-20kHz 0.00017 %
IMD (CCIF)PO=1W, f=18kHz+19kHz 0.00025 %
PO=10W, f=18kHz+19kHz 0.00022 %
PO=100W, f=18kHz+19kHz 0.00027 %
IMD (DIM)PO=1W, DIM30 0.002 %
PO=10W, DIM30 0.002 %
PO=100W, DIM30 0.002 %
Idle noiseA-weighted 11.5 µV
Dynamic rangeA-weighted 4Ω 131 dB
SNRA-weighted 4Ω 131 dB
Frequency responseRL= 8Ω, f= 20-20kHz ±0.01 dB
RL= 4Ω, f= 20-20kHz ±0.01 dB
RL= 2Ω, f= 20-20kHz ±0.01 dB
Output impedance1kHz, Iout=1A 0.07 mΩ
20-20kHz, Iout=1A <0.65 mΩ
Input impedanceRCA: 47kΩ / XLR: 94kΩ
Bypass: 2.2 / 4.4 
Power supplyAC 110 / 230V (Automatic detection of the input voltage)
Dimensions141 x 357 x 65mm
Weight1.8 kg
Power cableIncluded
Data sheet
OutputSpeaker terminal
Channel2 (Stereo)
ClassClass D / T
Amplifier chipHypex Ncore
Power (W)400.0

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Average votes
5.0 / 5
4 reviews
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Note :
Date :
Summer replacement for Accuphase Power Amplifier
These amplifiers (pair of monoblocs) have been acquired as a summer replacement for my Accuphase amplifiers which are warming my music room to extreme temperatures. Please be mindful that the review is written within first 24 hours of obtaining them and here you will find my initial thoughts which are nothing but subjective. The main concern for me will these amps have enough power to drive my B&W 802D3 speakers. The answer is YES, very much so. Both the deep bass and clear sweet midrange are exactly where they were and where I like them, Off course the treble is as expected, which is very precise. It is not too bright, it is nice. I dare say I am able to hear the decay of the cymbals or notes from piano with better detail than before. I am planning to test these amps for the next week or so and perform a detailed comparison to the Accuphase AMPs. So far so good. I am still worried that the Max power output is 227W which, as tested by ASR, give out continuous (RMS?) power of 131W. So far so good. Class D amps had a bad reputation in the past. I think that the Purify and Hypex crowd are changing the game and giving us music lovers (NOT Audiophiles - although the meaning is same) a whole new perspective on how music can be reproduces with high quality at an affordable price.
This review has been posted for AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm
Note :
Date :
Bon rapport qualité prix, il alimente une voie centrale Paradigm founder c90 avec brio, les voix sont claires et charpentés, tous les détails sont là. Évidemment il y a mieux mais bien plus cher. Je recommande.
This review has been posted for AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm
Note :
Date :
Incredible price performance
Anyone interested in this amp has probably dealt with measurement data and ASR. Thus, you know that probably one of the best power amps in the world is offered here.
They are impeccably finished and thoughtfully assembled. The sound is mercilessly transparent and clean. I can not imagine that there will be anything better again. Especially not for this price. This is final stage endgame.

A few criticisms: the front LED can be deactivated, but I would have preferred the color red or orange here, so that it is not so annoying at night. A small instruction or parts list, at least on a small piece of paper, would have been nice. But these are both really only small things.

Translated with (free version)
This review has been posted for AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm
Note :
Date :
good value, good customer support
This is a good value. For those of you who are accustomed to more old-school amplifiers, you will be surprised how such a light and small package can pack such a big punch. The internals of this unit will definitely make your speakers sing. The external case is good enough. Solid connectors. Simple design.

I ordered this to the USA based on what I've read about this implementation in online forums, particularly AudioScienceReview. The delivery arrived within days, in very protective packaging.

I needed to talk to customer support a few times, and they have been willing to address all my concerns in an ethical manner.

In conclusion, if you're in the market for a Purifi amplifier, I would recommend trying out the Audiophonics implementation.
This review has been posted for AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm
AUDIOPHONICS MPA-M400ET Mono Class D Amplifier Purifi 1x400W 4 Ohm
Class D mono power amplifier based on a PURIFI 1ET400A module and a HYPEX SMPS600A400 power supply.

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