Tube Headphone Amplifier


  • Overview
  • Gallery
  • Features
  • Specifications



Since our founding in 1962, we have sought to expand the limits of audio technology, pursuing an ever-changing purity of sound to foster human connections. Still, after six decades of discovery and innovation we felt it was time to take our analog audio exploration to an even higher level. The NARUKAMI series offers premium, boundary-pushing audio experiences, along with the meticulous Japanese craftsmanship that is an Audio-Technica hallmark.

Taking its name from the thunder god of Japanese legend, the NARUKAMI series features high-end audio products designed to ignite elemental passions. Our engineers rely on their refined auditory judgment, rather than a sterile set of technical specifications, to assess sound quality, while key materials, like precious KUROGAKI wood, are selected to bring the listener closer to the wonders of nature.

The top of the HPA-KG NARU tube amplifier/preamplifier is stylized like a dry landscape garden (karesansui), representing water flows that run down along the amplifier’s unique KUROGAKI wood side panels. The metal mesh cover protecting the vacuum tubes and output transformers recalls the dense pattern of the Ayasugi tree’s flat needles. These visual nods to nature prefigure the lifelike sound that awaits the listener.

The NARUKAMI headphone amplifier employs a fully balanced drive design, and all of the unit’s vacuum tubes are individually tested and matched to ensure optimal performance. The signal amplification stage uses a shunt regulated push-pull (SRPP) circuit design and employs paired JJ ECC83S tubes, known for their rich and resonant sound characteristics. In the power stage, two pairs of Takatsuki TA-300B tubes are utilized, delivering powerful driving force and dynamic high-quality sound.

The amplifier’s independent signal circuit and power supply for L/R channels ensure high separation and low noise, delivering transparent and rich sound quality for discerning audio enthusiasts. The amorphous core silver wire output transformer from Lundahl, chosen for its low magnetic hysteresis loss and optimal impedance matching, adds richness to the sound and provides flexibility with a headphone matching circuit.

But the NARUKAMI amplifier is not just a headphone amplifier; it also serves as a preamplifier with unbalanced RCA and balanced XLR pre-outs. The preamp is designed to amplify low-level audio signals from a source component, producing warm, natural sound from the vacuum tubes and bringing it to a level suitable for driving a power amplifier. The amplifier is also equipped with one set of unbalanced RCA line inputs and two pairs of balanced XLR inputs to allow connection of a CD/DVD player and other audio devices.

The HPA-KG NARU features two headphone jacks on the front of the unit: a 4.4 mm 4-pin XLR balanced jack for optimal channel separation, and a standard 6.3 mm (1/4") jack. An impedance selector switch allows you to choose the appropriate impedance (32–80 ohms, 80–250 ohms, 250–600 ohms) based on the characteristics of your headphones and desired sound quality.

To complement this high-performance amplifier we include a pair of our limited-edition AW-KG NARU headphones, featuring housings crafted from precious KUROGAKI wood. These headphones have been specially tuned to deliver exceptional sound quality and are equipped with A2DC (Audio Designed Detachable Coaxial) jacks for secure connection to the included 2.0 m (6.6') and 3.0 m (9.8') cables, each terminated with a 4-pin XLR-M balanced connector. As a special addition, we also include an interchangeable pair of ZMF Universe Hybrid earpads to provide a unique alternate listening experience.



  • Featuring KUROGAKI wood side panels and an Ayasugi-inspired metal mesh protective grille, the unit is stylized to reflect the beauty and power of nature 

  • The signal amplification stage employs paired JJ ECC83S tubes, known for their rich and resonant sound characteristics

  • Two pairs of Takatsuki TA-300B tubes are utilized in the power stage, delivering powerful driving force and dynamic high-quality sound

  • Circuit design features Lundahl input and output transformers, the latter constructed with amorphous alloy cores

  • Three-position impedance selector switch allows you to choose appropriate impedance based on headphone characteristics and desired sound quality

  • Two analog pre-outs (unbalanced RCA and balanced XLR)

  • Three analog inputs (unbalanced RCA and two balanced XLR)

  • Includes four replacement TA-300B vacuum tubes and a function explanation plate to aid in the use of the amplifier’s front panel dials and switches

  • Amplifier complies with the new safety standard IEC 62368

  • Included limited-edition AW-KG NARU headphones feature housings crafted from precious KUROGAKI wood

  • Includes two detachable fabric-braided headphone cables with A2DC (Audio Designed Detachable Coaxial) connectors at the headphones: a 2.0 m (6.6') cable with gold-plated 4-pin XLR-M balanced connector and a 3.0 m (9.8') cable with 4-pin XLR-M balanced connector

  • Additional set of ZMF Universe Hybrid earpads is also included for a unique alternate listening experience

  • Japanese craftsmanship: All Audio-Technica wooden headphones are hand-assembled in Tokyo

  • Headphones come with a wooden storage box adorned with KUROGAKI wood 


Headphone Amplifier
Circuit Configuration All-tube balanced amplifier
Headphone Impedance 32 to 600 ohms
Maximum Output Level Pre-output (10%, 1 kHz):
Balanced pre-output: 35 dB
Line pre-output: 29 dB
Instantaneous Maximum Output Level 6.3 mm (1/4”) headphone output (10% 1 kHz):
1600 mW + 1600 mW (32-ohm load)
1300 mW + 1300 mW (150-ohm load)
1000 mW + 1000 mW (600-ohm load)
Balanced output (10%, 1 kHz):
1600 mW + 1600 mW (32-ohm load)
1300 mW + 1300 mW (150-ohm load)
1000 mW + 1000 mW (600-ohm load)
Frequency Response Headphone output: 10 Hz to 60 kHz (±3 dB)
Pre-output: 10 Hz to 90 kHz (±3 dB)
Total Harmomic Distortion 0.8% or less (at 10 mW output, 20 Hz to 20 kHz)
0.08% or less (at 10 mW output, 1kHz)
Gain 6.3 mm (1/4”) headphone output / balanced output:
15 dB (32-ohm load)
17 dB (150-ohm load)
18 dB (600-ohm load)
18 dB (balanced pre-output)
12 dB (line pre-output)
Noise 6.3 mm (1/4”) headphone output / balanced output:
-98 dBv or less (A-weighted)
Separation Between Channels Single-end output: 68 dB (Load: 32 ohms, 1 kHz)
XLR4 balanced output: 100 dB (Load: 32 ohms, 1 kHz
Analog Input Terminal RCA jack line input x 1 XLR balanced input × 2
Headphone Output Terminal 6.3 mm (1/4”) stereo headphone output × 1 XLR4 balanced stereo headphone output × 1
Input Switching BAL1: Balanced1
BAL2: Balanced2
Output Switching PRE: Pre-output
XLR4: Balanced headphone output
HP: 6.3 mm (1/4”) headphone output
Headphone Impedance Switching 32: 32 to 80 ohms
150: 80 to 250 ohms
600: 250 to 600 ohms
Power Input Terminal IEC Type (Class I)
Power Supply 100 V AC, 50/60 Hz;110 V AC, 50/60 Hz; 120 V AC, 50/60 Hz
220 V AC, 50/60 Hz; 230 V AC, 50/60 Hz; 240 V AC, 50/60 Hz 115 W
(Switched with jumper wire inside product)
Power Transformer EI core transformer × 2 (L/R separated power supply)
R core transformer × 1 (for control)
Vacuum Tube TA-300B (TAKATSUKI) × 4, ECC83S Gold (JJ-electronic) × 4, GZ34S (JJ-electronic) × 2
Audio Output Transformer LUNDAHL (amorphous core, silver wire) × 4
Dimensions 493.5 mm (19") × 409 mm (16") × 352.5 mm (14") (W × D × H)
Weight Approx. 50 kg (110 lbs)
Accessories Included Vacuum tube (TA-300B) (replacement) × 4, Function explanation plate
Notes For product improvement, the product is subject to modification without notice.