Audio-gd Master 9 – Review

I’ve been wanting to write this review for a while now, but I wanted to gather all it was needed to do a proper job. First, I waited for the break in period, and now it has more than 220 hours. Then, I wanted to have all my headphones wired with good balanced wires, and I did manage do achieve that.

Master 9 was on my review list for a while now. I didn’t know anybody near me who had one and I was really curious about it’s capabilities.  After reading a few reviews, I decided I am going to buy one, and I must say that I am really glad that I did.

Looks, build quality and technical specs

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The Master 9  is a fully balanced headphone amplifier and and pre-amplifier.

When I first saw the pictures with M9 on the audio-gd website , I thought of it to be quite dull looking and lacking some finish. When I received the package and saw the real deal in front of me, I was very surprised to see a very nice looking amplifier.

The finishes are very good, better than I’ve seen in much more expensive products. It was quite heavy for a headphone amplifier(~16 kg), but that is the price to pay for  full class A. The chassis is made from a real sturdy heavyweight aluminium alloy and it feels like a tank.

When I said fully class A, I wasn’t joking. This is no marketing scam that  others use, saying that their amplifiers are class A, but forgetting to mention for example that only the first Watt is in class A and beyond that it goes in AB.

No, the M9 delivers 9W @ 40 ohm in pure Class A.

You can find all the specs you need on the audio-gd website.

I will mention some details that I found to be very important.

The core of the technology is explained well on the audio-gd website:


Master 9 is a true balanced design applying the newest ACSS design which can improve the XLR connection to sound as good as the ACSS connection. They seem complex , but in fact they are the most simple design the world has ever had , their a lot components to process the power supply. The simplest and shortest signal journey brings out the most neutral and least colored sound.
Master 9 applies ultra-low distortion single stage ACSS amplifier and soldered directly on the motherboard. It is a fully class A preamp / headphone amp and applies class A power supplies.

The ACSS is a non-feedback technology made with discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and non-feedback can’t do well in test measurements but can offer better sound for the human’s ears. Here is a conflict of the classic circuits. But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh. All signal gain is in current, all transistors work in pure class A mode.

The Master 9 output buffers had applied 4 pair power transistors ( 150W / 15A ) working on pure class A state, the output impedance is only 1 ohms , it can drive most headphones and amps as well .
Master 9 has all components of four channels exactly matched before installation.

Other important aspects:

  • Fully balanced pure class A design built by discrete analog stages without any OPA or coupling caps in the signal channels.
  • Total applied 12 pcs exact matching 150W transistors ( In total 1800W )  as the output stages and PSU stages for implement large class A output power .
  • Uses three R-core transformers (In total 135W ) separate power supplies for the digital  control components, right and left channels.
  • More than 55,000uf audio grade NOVER capacitors are used to ensure ample and smooth power delivery.
  • A total of 9 groups of  PSU’s for dedicated DC supply.
  • Uses most Hi-end grade parts and exactly matched transistors, OCC wires.
  • Four-channel 100 steps digitally controlled relay-based volume control avoids channel imbalance and improves sound quality .
  • Supper Exponential Volume Characteristic,  easy match the volume with very high headphone / speaker without change the gain mode.
  • The Master 9 output buffers had applied 4 pair power transistors ( 150W / 15A ) working on pure class A state,  the output impedance is only 1 ohms , it can drive most headphones and amps as well  .
  • Uses all audiophile grade components, including DALE resistors, WIMA caps, custom order NOVER (UK brand) caps, all audiophile grade input & output sockets (Neutrik ) and gold IEC socket.  Master 9 all parts of four channels had exact match before install.

Besides these, the M9 has some other very interesting spec values :

  • S/N Ratio >130DB (Input short, XLR mode)
  • THD  <0.002 %
  • Channels cross > 130DB
  • Output Impedance 1 ohm

Those are some very good values, values that I’ve seen in very few amps. Actually, I’ve seen some of these values only in Auralic Taurus MK2, an amplifier that is close to the price of Master 9. I haven’t had the pleasure of listening to it yet, but I most probably will find a test unit for a comparison in the future.

Edit: I had the chance to briefly listen to Auralic Taurus mk2 on different occasions and I wasn’t impressed at all. The level of clarity is not in master 9’s league.

You can find more about the technology here.

The power output on the balanced outputs:

40 ohm:   9000MW
100 ohm: 3800MW
300 ohm: 1250MW
600 ohm:   630MW

And on  single ended output:

40 ohm:   2500MW
100 ohm: 1050MW
300 ohm: 350MW
600 ohm:   175MW

Let’s take a look inside:

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I’ve seen some discussions on some forums with people that were afraid that the build quality wouldn’t be so good because it is Chinese. This product is proof that they are 1000% wrong. The design inside is incredibly clean and organized. Everything was done with attention and I am sure it took a lot of meticulous work.

The first things that grabbed my eyes were the 3 huge transformers:

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As I said, everything is very clean and organized:

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Some of the advertised occ copper cables:

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As you can see we have a variety of inputs:  2 single ended  RCA , 2 balanced xlr,  one ACSS Input.

It also has 2 balanced xlr outputs and one single ended rca output .

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The package also includes a very sturdy aluminium remote:

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These being said, this amplifier has incredible build quality, both inside and outside, and it can be set as example for a lot the western companies.

So, if you think that all products made in China have poor quality, think again!

Listening Impressions and Tests

The tests have been done with   Audio-Gd Master 9, MSB Analog Dac, AG500 Power Regenerator, Sennheiser HD800, Audeze LCD-3C, Audeze LCD-X, Focal Spirit ClassicFocal Spirit One, NAD HP50, AKG K550, AKG K545, Focal Spirit One S  .

I tried to plug Master 9 in the power regenerator. Even if the sound became a little cleaner, the sound lost dynamics, energy and attack. This shows that the amplifier already has a very good power stage inside and it doesn’t need any power regenerator / conditioning.

I’ve also tested it against my two amps at the moment : Decware Taboo MK3, Burson Conductor.

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I was really impressed by Master 9 from the first few minutes of listening. The transparency and details on it are just amazing. I’ve never heard such clean sound before. Bakoon HPA-21 had a clean sound too, maybe the cleanest after M9, but I don’t recall being so impressed by it’s transparency as with M9. One other important aspect is that Bakoon had a flatter sound that took away from the musicality and engagement. This doesn’t happen with the M9, as the sound is still natural and engaging when it needs to.

I’ve also tested M9 on both single ended and balanced outputs. There is a notable difference between these outputs. I used the same cable in the comparison. On the single ended output, the sound is a little sweeter with longer decays and slightly deeper bass, while the balanced outputs are more energetic with quite better details, faster sound in general, more punch in the bass, bigger soundstage and imaging.  These being said, even if the balanced outputs win, the single ended output is very interesting and very good as well.

I’ve tested a lot of portable headphones as well, sensitive headphones that don’t need that much power. All of them sounded excellent on M9 with no hum or other noise as it happens with the Taboo Mk3.

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Actually I loved all headphones with it. Even if Sennheiser HD800 scaled the most, both Audeze LCD-3 and LCD-X opened up with it too, giving them better speed, soundstage, transparency, details, impact, etc.

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One of these days, my father visited me and I’ve let him listen to both Taboo and Master 9. After a few minutes of intense listening (taping and feeling the music), my father said something very interesting about the difference between Taboo and M9. His words explained the comparison much better than I would have at that moment.

He said that with M9 the sound/music seems to have a full body that makes  you actually see the  sounds, while with Taboo the body of the sounds were not complete, comparing them to a hallow shell.

Practically, he said that while the sounds with Taboo were just like a hallow shell ,while  with M9 the sounds had the full body, not just the shell.

I find his words to be very accurate as the M9 has incredible transparency that leads to a very detailed presentation and actually more sound to be heard. The sounds are very clear and you easy to distinguish their extension from when they appear till they fade out.

Don’t forget that M9 needs a warm-up time before it sounds it’s best.

Let’s go through some songs and see how it stands.

Rodrigo y Gabriela- “Hanuman”

My mind was blown. I had to wait a little to pick up my jaw from the floor. I only have superlatives in my mind right now. Yes, this is that kind of audio gear, so please excuse me if you’ll get a lot of “amazing”, “incredible”, “awesome” from now. I cannot help myself, as I mean every word I say and I cannot tell a lie. The guitars on Master 9 were absolutely amazing. The plucks had an incredible attack followed by a very detailed extension. All of this is happening with an amazing pace and rhythm showing the speed, attack  and transparency Master 9 is capable of.

Pink Floyd – Another Brick in the Wall ( Part 2 )

Everything is just right. The drums are very punchy with very strong  impact and control. The guitars have excellent extension and feel. The voices are incredibly clean and detailed. The kids quire reveal a very big and well layered soundstage.

Paco de Lucia – Aspen

It was like I was listening to this song from a completely different perspective. I’ve never heard it like this till M9. Those guitars sound absolutely amazing on it. The attack on the plucks, the extension, the fluency and transparency of the sound are breath taking.

Nightwish – Wishmaster

I am rocking with HD800. Yes, you heard me. HD800 sound great even on rock with Master 9. ( Analog Dac has a saying here too ). M9 gave a very fast and engaging sound, with excellent PRAT that made me enjoy this song very much.

Hugh Laurie – Battle of Jericho

The transparency of this amplifier never seizes to amaze me. Everything is so clear and reveals all kind of details you never heard before. All the instruments are incredibly detailed and have amazing extension and natural sound. It’s like being there. The voices are very clean and fluent themselves.

Vivaldi – Autumn – Allegro (La Caccia)

I have never heard this song to sound better than this. The difference between taboo,conductor and Master 9 was quite big. On M9 the sound opened up, showing a much larger soundstage. The clarity and details of the instruments, the attack of the pluck, the natural decay weren’t second to anything I’ve heard till now.

Shostakovitch – Symphony No.9

The dynamics are incredible. Every instrument has it’s own impact, no matter how further away in the scene it is. Again, the soundstage is huge and presented in a very natural way. I felt like I was in the concert hall.

Rodrigo Y Gabriela – Syf

M9 strikes again. My jaw was on the floor. It was like I had the guitars right next to me. I closed my eyes and saw them near me. The extension, detail and attack of the plucks were out of this world.

Leonard Cohen – Going Home

Leonard’s voice is reproduced with amazing texture. It was so detailed and visceral that I felt it was getting out of my own throat. The female voices were amazing as well as they were incredibly clean and extended.

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The bass on Master 9 is very detailed, controlled, punchy and very fast.  It’s also as deep as it is told to be. It’s not going overboard nor the other way around. It’s just as it should be. I absolutely love it. It hits with incredible attack/punch and the control makes it the most detailed / accurate bass I’ve ever heard.


The mids are incredibly detailed and rich. Well, everything about this amp is great. All the instruments and voices have an incredibly detailed extension.


I’ve never felt that the amp is bright or sibilant. The treble was very clean, well extended and natural sounding.


Ladies and gentlemen, I present you the most transparent amplifier I have ever heard. It has the cleanest sound I have experienced until now, and the difference between it and the other amplifiers is not small. After Master 9, all the other amplifiers sounded dirty.


The transparency makes way for a lot of details you never knew were there. Don’t get me wrong, this is not an analytically amplifier, as it has the typical relaxed presentation of a class A amplifier.


The voices are amazing on M9. They are the cleanest voices I’ve ever heard. Adding the full and detailed extension and texture, they become regular goose bump producers.

Soundstage, Layering and Imaging

This is another area where M9 is just amazing. The sound just opens up with it. It’s like being in the concert hall. The layering and imaging are also superb, second to nothing I’ve heard till now.


While I’ve heard people saying that M9 is warm and others  to disagree, I reached the conclusion that Master 9 is very neutral. Because of this, it will sound as the rest of your sound system will tell it to. So depending on the cables you use and the rest of your gear, you can make it sound bright-ish or warm-ish.

Relaxed and Natural

I feel that even if the sound is fast and engaging, it is also relaxed in a good way, giving a very natural sound presentation.

Compared to Burson Conductor 

The bass on conductor seemed deeper, but Master 9 sounds more natural with a lot more faster, punchier and controlled bass. When I said that Conductor seemed to have deeper bass, it was just the first impression that came because of a smaller soundstage and less controlled bass. What I am trying to say is that Master 9 has the royal flush in the bass department as well, including the deepness and extension section. Actually, this is the best bass I’ve ever heard from a headphone amplifier until now.

Burson Conductor sounds closed in and dirty compared to Master 9.

So practically M9 has better bass, details, transparency, soundstage, imaging, instrument separation, etc. So, if you assumed that Master 9 is in a different league, you were completely right.

Compared to Taboo Mk3

Mk3 was my favorite amplifier, but now it has been dethroned by Master 9. Taboo has a “stronger” bass but slower and not so detailed. The sound is also fuller with a warmer tonality which could be more fun for some.  However M9 is still in another league as it is clearly  more transparent, detailed and faster.

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Considering all of the above, it is safe to say that this is the best headphone amplifier I have ever heard and tested. It has some areas where it is a few classes over what I’ve heard until now. I consider this amplifier to be  truly end game.

If you have a really good DAC, it would be a shame to use an amplifier that is not transparent enough, as it won’t let it shine to it’s maximum capabilities. Master 9 managed to make my MSB Analog Dac impress me one more time, as it reached another level with this amplifier.

I am sorry if I used too many superlatives, but this is one of those products that mark your listening experience throughout your journey in this hobby. I’ve meant and felt every word I said.

Audio-Gd has done a great job with it and I hope they keep it up. From what I have read, this amplifier compares with Headamp GSX – Mk2 and other very expensive amplifiers. Let’s not forget that Mk2 has a waiting list of more than 6 months or even more than a year. I would love to hear them side by side, but I have the feeling that M9 is one of the best headphone amplifiers in the world at this moment.

Besides this, when I bought it, Kingwa was very easy to talk to and everything went according to plan and quite fast. I had the amplifier on my table in less than 2 weeks.

Considering the performance of this amplifier and it’s price, it goes in the top of my recommendation list. Even Kevin Gilmore said that the design and components used in it are very good and if he had made it in USA, he wouldn’t even get the components with the money audio-gd is asking for the full product.

I must end this review thanking Kingwa and Audio-gd for this wonderful product and I really hope they will keep up the good work to amaze us with other products as well.


  • Incredible transparency (best I’ve heard)
  • Very good, spacious & holographic soundstage
  • Details…details everywhere
  • Incredible bass: very fast, controlled, deep, detailed and engaging. The most accurate bass I’ve ever heard
  • Very rich mids with incredibly extended and textured voices & instruments
  • Very extended and sparkly treble without sign of harshness
  • Incredible instrument separation, layering and imaging
  • Relaxed and natural sound presentation
  • Neutral sound
  • Lots of power and all of that in Class A. Basically, it can handle any headphone out there.
  • Very good match with all headphones I have tested it with
  • Good pre-amplifier
  • Very good price for this performance
  • Excellent build quality ( both inside and outside )
  • Very sturdy aluminium remote control included in the package


  • The feet are made of metal, so you cannot stack the M9 directly on other gear made of metal. If the feet contained some rubber like Burson has, it would have been perfect
  • Even if I consider neutrality to be a pro, some may see the lack of coloration as a con

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