GRAAF GM 400 power amplifier review


2014 marks the 30th anniversary of the legendary Italian high-end audio company GRAAF. I still remember how us audiophiles lusted over the unique and great looking black audio objects from the GRAAF some two decades ago.

It seems, that GRAAF was off the radar for few years, but actually nothing stopped at their headqurters. Mr. Mariani quietly worked on the new designs and Andrea Giovanardi joined the company and he's being in charge of company dealings with the industry.


GRAAF GM 400 was developed from ground up. It uses the completely  newly designed circuit. Mr. Mariani went all the way in his quest for something new and unique. He didn't copy the existent circuits or improved on the established ones, but developed a new one.

GRAAF is historically strongly linked to the tube circuits design, but interestingly new GM 400 is a full fledged solid state amplifier. So why the transistor based amplifier?“

Mr. Mariani new innovative concept being used with the new GM400 took him over 30 years of R&D. After innumerable trials and research, his concept was finally mature enough to implement it into a state of the art solid state power amplifier. This new circuit behave completely in a different manner in the terms of the driving the speakers. It was designed to guarantee absolute performance under any load or demand.

I asked Andrea and Mr. Mariani to answer few question regarding the company, new GRAAF GM 400 amplifier and high-end industry.

AG: Andrea Giovanardi and GM: Giovanni Mariani

MI: How and when did Graaf enter back into the audio circles?

AG: Someone spread around the fake notice that GRAAF went bankrupt, I'll use this occasion to clarify once for all that GRAAF never went bankrupt but had a standby period due to the fact that in 2006 some of the members of the old GRAAF crew start to focused on the new branches of the electronic like Domotics and home automations. Someone suggested to create a new company, but with the Italian law two different companies cannot exist the same roof, so Mr. Mariani, the father founder of GRAAF, decided to move away from the company and to continue to focused on the Hi-Fi and Hi-End. All happened in a peaceful way, the other company was founded and still today Mr. Mariani maintains a friendly relationship with them.

This reorganisation process took to Mr. Mariani more time than expected, but finally in the 2013 GRAAF officially came back in big style and with full GRAAF DNA Mr. Mariani could focus on new products and from these efforts the new GM 400 amplifier was designed.

GM: I'd like to add only that during this standby period we never stopped to R&D new products and solutions. This time was a great opportunity to test some of the new ideas that I've had accumulated in my mind for the last 30 years, but never had the time to put in practice. Some of those new concepts are now implemented in the GM 400 amplifier and others will find their application in the upcoming products.

MI: Do you consider yourself GRAAF an audiophile oriented company?

GM: Of course! GRAAF was created for demanding audiophiles who often go out and enjoy live music.

MI: You are doing everything in house?

GM: All the conceptual work is done in house and so is the final assembling and testing. We are proud to say, that all subsidiary  work is done by great artisans located in the local are near of  Modena.

Regarding the listening tests. We go directly to a lot of audiophiles in in Italy and even abroad. In that way we can test our products in their well known environment, collect their precious opinions and then use the information and suggestions at our laboratory to modify our product if necessary. We do repeat this process many times until both we and our audiophiles friends are sure that the product under development is ready for the market.

MI: How did GRAAF become such a legendary company?

GM: I don't know if GRAAF is a "legendary" company, but I'm happy enough to know that we have a serious reputation on the market and that the brand still continue to play a leading role among other brands. We are happy to play the David's role on a market full of Goliath.

I think that our main secret of success and broad recognition is  the courage to follow our ideas even if often those seemed to counteract with the current trends. All this combined with the passion and devotion for what we do let us stay focused and unique.

MI: Do you think we are on the to fast train of faster, bigger, better? Where do Graaf stand in this?

AG: We are not at all interested to jump on the train of faster, bigger and better. We rather follow our own train of slower, smarter, better way, thats run on a parallel railway.

MI: What is your opinion about tubes vs transistors?

GM: Due to my growing age I have a great sympathy for the valves. This was the "up to date" technology when I was a young student at the technical high school and making my first steps into the professional market. At the same time I've experienced the rise of the transistors and have always used them without preconceptions.

I think that is totally unnecessary to be sided with the transistor or the valves technology. For me its more interesting to investigate where and why each of those technologies can provide the best result.

Let me give a direct example. With the new GM 400 I didn't conclude, that transistors are better than tubes. I'm absolutely stay strong to my beliefs regarding GRAAF and tube. So the tubes models will soon follow in the near future. It's just, that in my long career in audio business and especially when I was the technical chief of Audio Consultants, I had the opportunity to listen to the best solid state power amps on the market.

At that time I could check the innards of those real Hi-End products and I never found a circuit that would totally satisfy me. In every one I found one more weak points and so I've started to contemplate about an ideal solid state amplifier circuit, that would solve everything I've perceived like errors in the transistor based amplifier. Out of this the GM 400 amplifier was being born.

MI: How do you see the holly grail of pure A Class in solid state amplifiers?

GM: Once again i don't have preconceptions. Honestly I have to say that at present it's possible to reach the same performance with more efficient and modern solutions.

MI: What are your musical references?

GM: (laughing) Unplugged live music.
AG: The letter G of GRAAF stands for group. A group of enthusiastic and not of business oriented people. An important member of this group is the archivist for several theatres in Italy. He have the exclusive permission to record all the events in these Italian musical temples. To do this he use a custom tube microphone preamplifier built by Mr. Mariani combined with  two custom microphones. All the recordings mainly recoded in digital and sometime in analog medium with a totally rebuilt Otari, that can operate at the double  speed (30ips). In connection with this project the legendary Neumann cutting machines is undergoing a restoration process. Our idea is to  drive the cutting head with a GM 400 amplifier.

Yes, our reference is live music as we visit the live events and record them at a very high technical level. In that way we're able to use those recording in replaying the same events in order to test our products.

MI: How do you see audiophile and high-end market?

AG: For GRAAF seven years in absence of the market dynamics was like falling a sleep in the renaissance age and wake up in the space age. The good news is that thanks to Mr. Mariani we woke up with the building plan for the Mars rocket in our pockets.

I read somewhere how one marketing guru explained, that nowadays if you can invest 100 units, you have to put 50 in the product and 50 in the marketing. We put 95% in the actual product and 5% in the marketing. In the less than one year since our return, we participed at the CES with our US distributor Avatar Acoustics and an Australian magazine classified the system in which the GM 400 plaid at the third place in the absolute terms among all the Hi-End systems present at the CES 2014. Other enthusiastic reviews are also coming out. For us this is a noteworthy result and a strong confirmation that there are still people interested in the real products and not being dazzled by the hyperbolic marketing campaigns.

MI: How do you see the GRAAF place in the high-end audio market?

AG: It's early to say and ultimately it'll be the market to decide where our place is and not us. We can only try to do our best in the everyday work.

Ideal place for us would be between the top brands in terms of quality and performance with the production volumes of a little artisan manufacture. This is how we love it to be.

MI: What are your plans for future?

GM: Soon we'll release a fully balanced tube preamplifier with unconventional performance. It will be in our style of doing things. The circuit is ready and we are now working on the mechanical and aesthetic aspects.

We also have a several ideas on how we would like to continue the research in the Transmission Line technology, started many years ago with the GM 100. We plan to rebuild the GM 20 with some updated solutions.

This GRAAF model seems to strongly remained in the heart of the enthusiasts as we receive almost every day a request for a refurbish them, request for informations or simply mail of congratulations. In Norway there is a dedicated club of GM 20 owners. This is very nice and give us the right motivation to go further with our work.

Another secret dream of ours is the starting of a "GRAAF recordings." We gained an important experiences and came with stand out results in this field and it would be a great pity to waste such experience. But, it all depend on market acceptance.

MI: Any words for our readers?

GM: Let's us all enjoy as many live concerts as possible!


GRAAF GM 400 came in an interesting high-end audio period. Last and this year I've had a luxury of hearing many upper echelon amplifiers, that created a strong authority. Things certainly moved forward with the performance in high-end audio generally, but still, the real advance is a luxury of only handful companies.

Transcribing my listening notes into the fluid reading might be a tedious job, but the mind's urge of exploring great musical machines keep my determination and focus intact :). It's always feels complex to convey what I feel and hear it into the broad language, that would compel to my readers in the most digestible way.

GRAAF GM 400 showed a very balanced presentation across the whole frequency range and interestingly it spotted a truly remarkable reproduction of the higher frequencies. To often with a modern amplifiers we have to deal with the artificially boosted high-frequency spectrum, but GM400 smitten me with its open, transparent and life-like impact and presentation. Many of those amplifiers bring the feeling of the brick wall filter effect. In such performance most amplifiers fail in their claims of highly regarded state of the art design and audio reproduction.

With GM 400 I've experience something I usually associate with the greatly designed tube amplifiers. The ease and natural pace of music, that brings the reproduction closer to what vocals, instruments and live music actually sounds like. GM400 managed to keep the fluidity and smoothness of vocal based music like few solid state amplifiers can. I highly relay in my listening test to to the live experience of the music. Un-amplified acoustical live music recorded in the natural ambiences is still the only ultimate reference for me in my critical judging.

GM 400 brought the level of reality I normally don't associate with the solid state based amplifiers. It clearly shows, that Mr. Mariani knows his craft. As mentioned above in the interview, GRAAF musical performing references are affected by live acoustical music. This is a great way to tune and refine any power amplifier or high-end audio product in general sense.

You can never failed to recognise a DNA of audio designer being implemented into his products. It's a matter of choices being made and how one sees and prefer the musical reproduction. The great sense of music and energy is strongly associated with the GM400 ability to create the energetic and realistic sense of music in the listening room.

In my book this is strongly associated with the structural part of dealing with the signal gain. GM 400 has a high output, which I welcomed with an open arms. In getting all needed for the complete and balanced presentation this is a crucial attribute. Dealing with the lower audio gain brings a set of their own problems in recreating the musical event. In my twenty some years of high-end audio listening I'm more inclined to dealings with higher output gain regardless of the components. It needs to works under basic rules, but the energy flow is highly regarded with the proper higher gain distribution.

It was interesting to try the GM400 with the latest LessLoss DFPC Reference power cable. I wanted to see how it would perform with the latest flagship power cable from LessLoss. As with most amplifiers, the difference was instant. The LessLoss power cables have this inherent ability to shift the performance to a higher plane, at once, without loosing the impact of natural dynamic simplicity. With the GM400, the performance boost was even more obvious than usual. The synergy between those two was great. The LessLoss Reference power cord and the GRAAF GM400 really seem to compliment each other in a great way. For sure, this is a great and must addition.


I've spent most of the listening time with GRAAF GM 400 listening to my vinyl records. Going through my collection of 45rpm versions of my favourite albums was really a nice roundtrip into the music history.

GRAAF GM 400 showed the strong ability to move with the musical pace across wide selection of albums. With Cannonball Adderley Know What I Mean? 45rpm vinyl album I can instantly recognise either the amplifier is able to recreate the mood of Julian Edwin saxophone playing or just blend with the accompanied music. He's sensible playing can quickly become lost in translation with power amplifiers that were designed without the real focus on the music. In this great 1961 album by Julian Cannonball Adderley, is accompanied by legendary Bill Evans and the rhythm section of the Modern Jazz Quartet. The synergy can be felt and the musicianship is one of the kind. This was the era of one of the kind musical output and the artist seems to came from a completely different universe.

There is a certain aura and energy attached to these unforgettable recordings. I'v had a luxury to hear some of the analog tapes of the jazz and classical recordings and what I've experienced made an lasting imprint on me. Large portion of the energy impact is still shared on the vinyl. Great enough, but not the same.

From these memories and with high quality vinyl pressings I'm always critically judging the reproduction of any product under the test. It's the ability of any so called high-end audio amplifier to evoke the level of the emotions and energy of music being replayed, that makes it worthy of putting the high-end audio prefix and call it believable.

GRAAF GM 400 comes from the hand of the designer, that always took a bit different route. He knows the real music and follows its pace. This reflects in his design choices and in the way that music is being reproduced through his products.

GM 400 power amplifier never seems to lost that inherited ability to move me towards the familiar recording music in very involving way. This was clearly shown with another great 45rpm vinyl album. Acoustics Sounds release of the Nat King Cole Love Is A Thing.

Love Is the Thing was a true chart topper album in the early LP era. It's success was driven by the Cole's rendition of "When I Fall in Love." The magic of Gordon Jenkins classical orchestrations on the album is one of the kind and adds greatly to the positive energy of Nat. You can feel in Nat King Cole music, that he was a good man. He was trained classical piano, but quickly took over his love; the jazz.

Nat King Cole is another legendary artist of the golden era of music. I grew up to his music and ability to hear him in his best with Analogue Production 45rpm version of Love Is A Thing feels magical. This vinyl release brings so much of the "real analogue" tape feeling, that is a must have not only for any Nat King Cole fan, but all the jazz and pop music lovers. This album can show how well is your system balanced and it puts forward any week point of a complete system part.

GRAAF GM 400 power amplifier managed to embody the spirit and the energy of this album in a grand style. You can really feel the massive energy of Cole vocal coming through the speakers and lifelike enormous force of his vocals is thunder like. This is the ultimate test for any power amplifier ability to let through the emotional energy flow. GM 400 passed this test remarkably.


GRAAF GM 400 is no mass made high-end product. It's manufactured in smaller quantities and in an artisan way of doing things. It's clear, that Mr. Mariani and Andrea perceive the music in a different way. They cherish it profoundly and the GM 400 is a clear result of their passion and dedication.

In the times where everything is driven by the massive industry urge of fast and furious, Mr. Mariani creates his products with a slower pace. GRAAF GM 400 feels and sound like a matured first class wine. The quality of musical reproduction in on the warm, life-like side and the upper frequencies seems to disappear into the space and time seamlessly without making any traces of unevenness.

GRAAF GM 400 amplifier brings the level of reality, that puts it in the company of a true high-end audio contemporary amplifiers. I never felt with GM 400, that music was holding back. The dynamic impact and fluidity were on par with the amplifiers costing much more then GM 400. GRAAF GM 400 clearly defies its size and price point.

In all my listening hours GM 400 never felt like an typical solid state amplifier. In analogy, solid state power amplifiers tend to bring enormous energy down trough the tight pipeline, that relates to the speaker driving and many lost their musical appeal in doing so. The energy might be there, but the sense of musicality is lost forever. On contrary greatly designed tube amplifiers do it with much easy grip and GRAAF GM 400 felt exactly like that.

GRAAF GM 400 power amplifier never acted in a forceful harsh way or in brining its character onto recordings. It kept the pace flowing with the detailed and balanced reproduction.

In my listening notes I marked and highlighted a few times how along the tube sound reference it reminded me closely also to the best characteristics of pure class A solid state amplifiers. The smoothness and fast pace is a demanding task for any solid state class A amplifier, but when designed properly such amplifier can bring quite heavenly performance. GRAFF GM 400 reflected those attributes repeatedly. Best of the both worlds. In its special AB Class circuit GM 400 works in a sustain with the A Class, which is alway active. This ensure the sound, that is beyond AB class beyond typical approaches and offers a GM 400 unique performance.

It was great to hear GRAAF product after over a decade or more again. GM 400 kept all the attributes of a classical GRAAF amplifiers, but with the intriguing solid state design, that proved to be as unique and special as Mr. Mariani tube amplifiers.

GRAAF GM 400 comes with the great military flight case, that protects the amplifier from all sides with the internal foam.

A real 21st century power amplifier with the spirit of the great tube amplifiers. GM 400 is really small in size compared to the big oversized chassis we might be used to these days. Despite this it acts with the authority and power, that has nothing to do with the smaller size.

This is highly unique amplifier. Recommended!


Power rating into 8 ohm and 4 ohm: 220W @ 8 OHM - 370 @ 4 OHM
Total Harmonic Distortion at the rated continuous power: THD @ 1Khz : 0.4% @ 8 OHM - 0.4 @ 4 OHM
Power Bandwidth for this power rating (20hz-20khz): 220W @ 8 OHM - 370 @ 4 OHM
Signal to Noise Ration: 102.5 dbA
Voltage Gain: 50v = 31.6 dB
Frequency Respons: >200Khz
Rise Time: 1.2uS
Slew Rate: 42V/uS (and more but a more accurate test is distructive)

Damping factor:

DF @ P. out 1W = 13,80
DF @ P. out 10W = 20,90
DF @ P. out 100W = 36,25
DF @ P. out 200W = 37,24

Input impedance: 47Kohm (UNBALANCED) 94Kohm (BALANCED) the first lot
Output impedance: INDIFFERENT BETWEEN 4 TO 8 OHM
Energy Storage (size of power supply per channel and total): 110.000uF TOTAL
Output device type (Bipolar or Mosfet) along with input device type: BIPOLAR
Feedback: No global feedback, only local in the driver stage.
Number of gain stages: 3

Power Consumption
Idle power draw: 68W
Full Rated Power: 740W

Product dimensions and weight: 400mm X 385mm X 160mm - 18.6Kg

Shipping dimensions and weight:
MILITARY CASE 13.4Kg - 670X510X262mm
VOLUME: 56.1lt/14.79

Price: 14.900 EUR

Mono and Stereo ultra high end audio magazine 2006-2014.