HE9-MKII - Flagship Headphone Amplifier
HE9-MKII - Flagship Headphone Amplifier
HE9-MKII - Flagship Headphone Amplifier
HE9-MKII - Flagship Headphone Amplifier
HE9-MKII - Flagship Headphone Amplifier
HE9-MKII - Flagship Headphone Amplifier

HE9-MKII - Flagship Headphone Amplifier

CHF 2,899.00

Delivery time on request.
(All devices are handmade to customer order)


  • Renewable power supply works as a dedicated power generator
  • True balanced ACSS Pure Class-A headphones and preamp

What's new on the HE-9 MK2?

  1. The preamp output has built in the exclusive output buffers, which can improve the sound quality of the preamp output.
  2. Dual volume control can address different sources with the different output levels.
  3. Redesigned left and right channel boards for improved sound quality.


  • Unique fully analog regenerative power technology as built in a private power generator, providing the cleanest power supply, increase the sound quality more transparent, but analog, much better than the external digital technology power processor, not to say the passive LC Power filter outlet.
  • Unique true ACSS non-reactive headlight adopts four channels of non-reactive output stages, which consists of 8 pieces of transistors, each piece has 15A/150W power. The capacitance of the whole machine reaches up to 60,000uF. Four R-core transformers with a total power of 260W are used.
  • The preamp output has built-in exclusive output buffers, which can improve the sound quality of the preamp output.
  • Separate Class A power supplies power the regenerative drivers and the audio signal amplifiers.
  • Four-channel 100-step relay-based digital volume control avoids channel imbalance and improves sound quality.
  • Four-channel 9-stage digitally controlled, relay-based pre-volume control can adjust the source input level from 0DB to -9DB.
  • Two gain modes, high gain has 20DB and low gain has 10DB, which is more flexibility for different gain power stage.
  • 5 analog inputs: RCA X2, XLR X2, ACSS X1 (also with RCA or XLR inputs, the output still has ACSS available)
  • 3 preamp outputs: XLR / RCA / ACSS
  • 4 headphone amplifier outputs: 6.3MM / 4 pins XLR / 3 pins XLR *2

Current Conveyor Technology detail

Unique all-analog regenerative power technology:

While audio is life, power is water. Pure water creates wonderful life, clean power supply reproduces wonderful sound.

The regenerative power supply is built into the device like its own electric generator. It can block most of the interference from the power line, provide ultra-clean power supply for the audio amplifiers, reproduce the most neutral and analog sound of the audio signal for the system and users.

In the regenerative power supply, the AC power is over converted to DC through the input regenerative transformer and passed to the regenerative wave generator and driver stages via the Class A power supplies.

A balanced regenerative wave generator produces an extremely low-distortion 50 Hz wave, which is balanced by the equalizing amplifiers and the strong output stages is passed. The regenerative transformers produce a clean AC power supply that feeds the separate Class A power supplies for the L and R channel preamps.

The Class A parallel circuit PSU has a very high input impedance to avoid That interference from the PSU from affecting the signal parts, and low output impedance with very fast speed and high linearity, it is a very clean power supply.

Unique true ACSS non-feedback/preamp technology

The HE-9 MK2 was built in a really balanced design using the latest ACSS design It seems complex but in fact they are the simplest design the world has ever had, its a lot of components to handle the power supply .

The amplifier built into the HE-9 MK2 has only a single "voltage gain stage" for signal processing, but operates in ACSS mode, so it is actually a current gain stage instead of a voltage gain stage, while normal OPA chips already have two or three Voltage boost stages included. The simplest and shortest signal path produces the most neutral and least colored sound.

The HE-9 MK2 uses an ultra-low distortion single-stage ACSS amplifier soldered directly to the motherboard. The amplification stages and the diamond cross output stage operate in pure Class A operation.

ACSS is a zero-feedback technology that uses fully discrete amplifiers. Most people know that the global feedback design can perform better in test measurements, and non-feedback does not perform well in test measurements but sounds better to human ears.

There is a conflict between the classic circuits here. However, the ACSS opens up a new field as it can offer a less colored, more neutral sound with very low distortion and high linearity. So it can keep the dynamics, detail and neutral sound but not sound bright or harsh.

All signal amplification is in the form of current, which is achieved by the unique excellent open-loop multi-output mirror. The result is incomparably precise and extremely low distortion of the amplification signal. The entire signal path is balanced and all transistors operate in Class A mode.

The HE-9 MK2 uses four channels of open-loop output stages consisting of 8 transistors, each rated at 15A/150W. The capacitance of the whole device reaches 60,000uF. Four R-core transformers with a total power of 260 W are used.

Unique I/V conversion volume control technology

The volume control also differs from conventional technology. Conventional volume control technology is to implement the volume control in the analog amplifier input stage through a volume control potentiometer to reduce the signal. The quality of the volume control directly affects the sound quality. With low quality volume control, details are lost, and imbalance of channels leads to distortion of the soundstage. Even the high power volume potentiometer, in the attenuation then gain the signal mode, still cause the detail to be lost and cause the S / N worst.

In the HE-9 MK2, we have the I/V conversion volume control, the volume control only has a variable passive I/V conversion place 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 won't lose details.

It cannot degrade the sound quality at any volume. According to the volume, there is diamond cross output stage which can provide the very low output impedance.
The quality of the volume control is very important in the real balance gear.

It must guarantee the four channels signal control accurately to achieve the performance of the real balance gear If the cool and hot of the balance signal can not guarantee accurate, the balance output has large distortion will cause the sound quality and performance even much worse than a single end gear, the balance gear design and waste wasting the cost.

In HE-9 MK2, a four-channel digital control relay-based volume control is applied, by changing the resistors 0.05% tolerance, to achieve the best performance and avoid the volume for the channels unbalanced To control the sound quality of the transmission.

HE-9 MK2 have 100 steps volume control, applied supper exponential volume characteristic, easy to match the volume with different power amplifiers and speakers. while changing the volume, the different relays break or close, it can had slightly changing sound at the output and disappear while Stop change the volume.


HE-9 MK2 has a complete separation of the left, right amplifier channels, regenerative drivers and transformer, also the 230V / 120V power input lines had shield in the two thick aluminum plates.

The HE-9 MK2 uses a heavy all-aluminum body to prevent the eddy current from the transformers from interfering with the circuit board.

S/N Ratio


THD+N <0.0025%

Frequency Band (XLR input)

20Hz - 100KHz (<4DB )


Volume characteristic

100 steps Supper Exponential Volume Characteristic

Headphone amp Output Power
(Balanced class A )

25 ohm: 15W
40 ohm: 10W
100 ohm: 4W
300 ohm: 1350mW

Headphone amp Output Power
(Single-ended class A )
25 ohm: 4W

40 ohm: 2500mW

100 ohm: 1000mW

300 ohm: 350mW


High gain :+20DB
Low gain : +10DB

Output Level (Max)

9.5V @ RCA
19V @ XLR

Output Impedance

10 ohm @ preamp XLR
2 ohm @ headamp balanced output

Input Impedance

94K ohms @ XLR
<5 ohms @ ACSS

Channels cross
< -130DB

Channels imbalance
< 0.01DB

Power Requirement

1 version 100-120V AC 50/60 Hz
2 version 220-240V AC 50/60 Hz

Power Consumption

66W Class A @230V or 120V

Transformer Power

260W (3 unit transformers)

Package Weight

Approximately 20KG

W430 X L485 X H123 (MM, Fully aluminum )


Power cord X1