Audio-GD Master 9 MK3 - Dual Mono Headphone Amplifier
Audio-GD Master 9 MK3 - Dual Mono Headphone Amplifier
Audio-GD Master 9 MK3 - Dual Mono Headphone Amplifier

Audio-GD Master 9 MK3 - Dual Mono Headphone Amplifier

CHF 1,399.00

Delivery time approx. 2-3 weeks.
The devices are manufactured on customer request.


  • True dual mono design ,Uses two R-core transformers  separate power supplies for the right and left channels.
  • Non-feedback ACSS gain stage and non-feedback diamond output stage.
  • Fully balanced pure class A design built by discrete analog stages without any OPA or coupling caps in the signal channels.
  • Total applied 8 pcs exact matching 150W transistors ( In total 1200W ) as the output stages  for implement large class A output power.
  • More than 32,000uf audio grade NOVER capacitors and 4 groups pure class A PSUs power supply are used to ensure ample and smooth power delivery.
  • Four-channel 100 steps digitally controlled relay-based volume control avoids channel imbalance and improves sound quality .
  • 16.25DB in total 2 type gain modes can drive the low sensitivity headphone very well.
  • 4 groups input: RCA X1, XLR X2, ACSS X1
  • 3 groups preamp output: XLR / RCA / ACSS
  • 2 groups headphone amp output: 4pins XLR X1 / 6.3MM X1


Technology Detail

The Master 9 is a true dual mono design and a true balanced design, using the latest ACSS design, which can improve the XLR connection to sound as good as the ACSS -Connection. They seem complex, but in reality they are the simplest design the world has ever had, their a lot of components to handle the power.

The Master 9 uses an ultra-low distortion single-stage ACSS amplifier that produces the most neutral and least colored sound with the simplest and shortest signal path. the components are soldered directly to the motherboard.

ACSS is a zero-feedback technology that uses discrete amplifiers. Most people know that the global feedback design performs better in test measurements, while the non-feedback design does not perform well in test measurements, but provides better sound to the human ear.

There is a conflict between the classic circuits here. However, the ACSS opens up a new field; it can offer a less colored, more neutral sound with very low distortion and high linearity. This allows it to maintain the dynamics, details and neutral sound without sounding bright or harsh.

All signal amplification occurs in current mode, all transistors operate in pure Class A mode.

Powerful Class A output stages:

The Master 9 has 4 groups of diamond differential output stages as a balance drive stage, which have four pairs of 150W transistors also operating in pure Class A state.

The pure Class A design has a greater driving capability than the specifications, it drives the headphone no worse than a Class AB design with twice the power, not to say the pure Class A design is that best sound design worth.

The balance drive mode can kill the noise and distortion in the end of the headphones, much improve the soundstage, background and transparency, ect.


Power supply:    

Two dedicated transformers and 4 groups of pure Class A power supplies are used to power the left and right channels separately.

The Class A parallel switching power supply has a very high input impedance to prevent pulses through the power supply from affecting the preamplifier and a low output impedance with very high speed and high linearity, making it a very clean power supply.

Volume control:

The volume control is also different from traditional technology. Conventional volume control technology is to implement volume control in the analog amplifier input stage through a volume potentiometer to reduce the signal.

The quality of the volume control directly affects the sound quality, a poor quality volume control results in a loss of detail and an imbalance of channels results in soundstage distortion.

Even the high performance volume controls still cause the detail to be lost. Regardless of the quality of the potentiometer, the S/N must be worse.

But in the Master 9 we have the I/V conversion volume control, the volume control only places a variable passive I/V conversion at the ACSS amplifier output, where the output is the current signal, not the voltage signal.

The volume control is an I/V conversion, and the volume depends on the conversion of current (I) to voltage (V). (Like R-2R D/A chips that output passive I/V conversion) It can keep the signal frequency band flat and does not lose details. It cannot degrade the sound quality at any volume. According to the volume, there are four groups of diamond non-feedback buffer output stages to provide the very low output impedance.

The quality of volume control is very important in real balance transmission. It must guarantee the four channels signal control to accurately achieve the performance of the real balance gear. If the cool and hot of the balance signal can not guarantee accurate, the balance output will have large distortion causing the sound quality and performance even much worse than a single end gear, wasting the balance gear design and the cost.

In Master 9, a four channel 100 steps digital control relay-based volume control is applied, switch the 0.1% resistors to guarantee accurate control for the four channels of the balance amp. While changing the volume, the various relays break or close, it may have had slightly changing tone at the output and disappear while changing the volume.