Analog Domain M75D Stereo integrated amplifier review preview

Analog Domain as a brand needing no introduction at the pages of the Mono & Stereo. Still, to refresh the memory. Analog Domain is a brainchild of charismatic audio designer Angel Despotov. His life long experience in both pro and high-end audio and decision to bring something of difference, led to establishment of a unique ultra high-end audio venture, that goes by the name Analog Domain.

For Angel the name reflects the fact that we live in analog world and he focuses on the analog circuit designs, which in his opinion outperform digital by a significant margin, and he’s more then sure, that they always will.

I’ve had a luxury of meeting Angel in person few times and spent  prolonged hours talking about the music, high-end audio and joint listening. His mind operates in a different way and with the both “by the book” and out of the box sets of rules. These is clearly audible from the even from the first few songs played through his creations. For Angel solid state is the way to go as he strongly believe in its high performance, long service life and consistent quality. On contrary to many strong opinions Angel feels, that for the listening to the music at natural levels high power output is a necessity. 

So even with M75D integrated amplifier you won’t stumble on a shy few dozen of watts. It stands cemented with the manly step size, authority and guide…


In the times of so called high-tech advancements many claims AB class power amplifiers are forsaken. I’m still waiting for any class D amplifier to become pensive. Many class A and AB amplifiers follows such route quite closely.

Let me slide into the more complex and “touchy” side. For some this might be to esoteric or even to technical. Yet, I really feel its needed to lay down the building blocks that differ so much around M75D integrated amplifier. 

With intriguingly vast amount of amplifier designs I’m too quickly affected with the interictal phenomena. This is not on the clinical side of the seizures, but more connected to the uncanny feeling, slightly or more pronounced uncomforted feeling. Depends on the product and design. Exploring this further resolves in an interesting pattern recognition. This seems to be closely connected to the high-frequency oscillations. Class D rings a bell?

There are quite some scientific explorations pointing into this direction. I always do my homework, especially as I wanted to find the common ground of why especially 80 -500 Hz frequency range is so affected with the actual listening affect. This range is one of the foundations of the enliven, potent and “materialized” three dimensional sound, that can create an emotional, interactive exchange of music and forms the needed energy flow. It’s also the objective range for laying the grounds of palpable illusion and M75D is no rookie witing this territory. It shows where the research, time and importance was dedicated to. 

The amplifier design is only as good as factual sonic output. Lurking further into the M75D performance of the last two octaves ranging approximately from 6 - 20 kHz reveals the grainless and feather like rendition, that is not exactly as a fact connected with even most expensive amplifiers, be it integrated or power.

This also where the “S” hubris takes its part and clearly one of the biggest reason why so many amplifiers presents unpleasant sibilants. This “phenomena” is usually associated with peaks at around 7 Khz. 

Human vocals are the most instant and primal source of critical, reference listening. The flow and energy impact connected to the recognizing three dimensionality and air/breathing flow is of utmost importance. This is more closely connected to the 15 kHz where also the metallic hisses on the rides, cymbals, hi-hats and all other metallic instruments timbres are instantly evident when things are not executed properly. That’s why the measurements and practical listening must go hand in hand. There is simply no easy way of doing things in right direction when it comes to the state of the art amp conceptualization and realization. No shortcuts can lead to creation of an amplifier, worthy of the high-end audio labeling. 


So why I’m fond on Analog Domain gear? For many reasons. Angel is taking both measuring and listening part utmost seriously. He managed to liquify the pure Class A sonics with Analog Domain proprietary circuit AB technology, that works with minimum heat dissipation. 

For me The M75D falls into the camp of very few products being able to reconnect the listener with the music for what it is. Rich, palpable and emotionally impacted, something we should cherish as a only holly grail. Music is of such empowered potency that can relate to the peoples inner world and materialize something special and lingering. Sad part is, that many of the current high-end product just offer a shiny, blinding shelf, a bling package, without actually being able to carry the musical message intact. 

The M75D work in the domain that vividly reflects Angel mind set. This integrated is fully charged with pure Analog Domain DNA and can transcribe a profound, enriched musical message across the “wire” unaltered. 

Among all other things we’re dealing with a subtle physical phenomena of transferring the energy across the “wire” is essential. When music is slow paced then amplifier should follow. When all morphs into the lightning fast experience it should relate to such time change instantly. You cannot change the formation of the attack, delay, sustain and release at any point if you want to keep the realistic impact. Nothing should be lost in the translation of the music via high-end audio system. Period!

To the next point intimately associated. The flow of the music! Most current designs belong to the camp of mediocrity and blank transcription. If music does not relate instantly to the rhythm and pace it simply cannot flow properly and potently. Facts of reality stands still. Only rarely synaesthesia arise and this is closely related to the dynamic simplicity, something about what I’ve already elaborated many times. Exploring the dynamic simplicity logically encapsulate linearity and coherence, further translating to the time dimension impact. Imagine piccolo and grand scale of atomic leveling tier related intervals forming an ultra complex network of decays, delays and reverberation points. Analog Domain M75D exhibits expansive amount of attributes and focus points needed for the recreation of time domain related advanced attributes. 

Contemporary high end audio integrated amplifiers tend to perform up to the certain level where you’re only allowed to lurk into the woods without ever entering. Analog Domain M75D is an epitome integrated amplifier in this regard and non perilous concept. It was design to last and impress with the scenic sound output. 


In reality dynamic amplitude determine the loudness of the energy impact. This goes beyond audible and when amplifier is designed properly you don't hear instruments distorts per se.

This prolonged to a crest factor in live sound and translates to how much the peaks are above the average level. In a live performance you’ll easily get 20-26 dB peaks above the average sound level meaning 100-400 much more power for the peaks, relative to the average level. If you’re listening at only 10W of average power on a system of 90 dB, you would get 100dB average, and you would need actually a 4000 W for the peaks for everything to sound natural. So 400 times (+26dB) 3dB = double power…

This reveals interesting facts and the logic behind much needed power, especially with the modern dynamic speakers. Its not strange why there is a lack of musical flow that is essential for recreating the live musical experience. Summing all up logically refers to the discussion of to much power. Reality strikes. How can you jump five meters in a room that is only three meters high... This is a perfect analogy regarding to the proper power implementation.


Analog Domain M75D implements unique The Excalibur Circuit and M75D is the first brand product with it in a serial production.

"The figure below shows a highly simplified schematic of the M75D power amp stage. We have named this topology “The Excalibur”, knowing you understand the humor ;) The main difference from popular topologies is in the final stage topology - the output devices are connected in a “common emitter” (CE) rather than the popular “common collector” (CC), also known as emitter follower, Darlington configuration. The drive currents in a CE configuration flow between the supply rails and ground and not into the load as in CC, leading to improved linearity, among other benefits. Despite its advantages, the CE topology is not popular as it is prone to thermal runaway and self-destruction if conventional bias control methods are attempted. Our proprietary DXDriveTM technology resolves this “minor inconvenience”, allowing us to take full advantage of the superior common emitter topology. "

One notable advantage of the Excalibur topology is its unrestricted current delivery capability. The internal resistance of the circuit is essentially zero as there is no local current feedback loop in the signal path. There are no “difficult loads” for the Excalibur. The near-zero internal resistance reduces back-EMV-induced distortion when driving loudspeakers. Back-EMV1 created by loudspeakers and its interaction with the output resistance of a power amplifier is a significant contributor to overall distortion and is one of the reasons why most NFB designs fail to perform adequately with real world loudspeakers. The Excalibur uses multi-point negative feedback to vastly improve performance over conventional NFB or non-NFB designs. 

Only protection circuits limit the current output current of the M75D. The protection circuits would disable the output stage if the load attempts to draw current in excess of the safe maximum. Normal operation resumes automatically when the overload condition is remedied, e.g. when a short circuit is removed.

To be continued…

Text: Matej Isak