Cayin HA-300 MK3 black

Third generation of Cayin’s flagship headphone listening product, the HA-300 MK3 retains the pure Class A single-ended (SET) topology built around directly heated 300B triodes, a formula the Chinese brand has been refining for nearly a decade. Revised circuitry, next-generation transformers, redesigned power supply and expanded compatibility with sensitive IEMs: this iteration does not change the philosophy, it takes it further.

Two chassis, one isolation principle

The HA-300 MK3 physically separates the amplifier and its power supply into two distinct enclosures. The idea is simple: keep the power transformers and their magnetic field away from the audio path to limit interference, vibrations and residual noise. The two units communicate via a lockable aviation-type connector umbilical cable, which secures the connection and reduces losses. The terminals are protected from dust when the cable is disconnected. This design choice was already present on the MK2, but Cayin announces dedicated work on EMI isolation and chassis mechanical rigidity, helping to lower the noise floor.

The assembly has considerable weight: 16.8 kg for the amplifier (286 × 368 × 205 mm) and 10 kg for the power supply unit (159 × 345 × 205 mm). This is a desktop unit designed to stay in place.

Transformers designed and wound in-house

Transformers are a critical element in a transformer-coupled SET amplifier: they directly shape tonal density, soundstage and transient behavior. Cayin designs and winds its own in-house, a know-how few manufacturers still master today. The MK3 introduces a third generation of wide-band EI output transformers and toroidal power transformer, both optimized for this platform.

Compared with previous versions, Cayin claims enhanced shielding, lower residual ripple, reduced interference and a more stable power supply. The wide bandwidth of these transformers promotes consistent reproduction across the entire spectrum. The result naturally depends on the rest of the system, but mastery of the output transformer is a structural advantage in this topology: it is what “speaks” to the headphones.

Six tubes, a minimalist circuit

The SET philosophy is based on signal path simplicity. A single power tube per channel (the 300B) amplifies the signal without splitting it, preserving the even-order harmonics prized in high-fidelity listening. The voltage stage uses a pair of 6SN7 tubes, a classic match for the 300B, while rectification is handled by two GZ34 / 5AR4 tubes.

The MK3 comes with a selected tube set: two Genalex Gold Lion PX300B output tubes, two JJ 6SN7 driver tubes and two JJ GZ34 rectifier tubes. Each tube is tested, matched and subjected to a 48-hour burn-in at the factory before shipping. The move to GZ34 tubes (the MK2 used four NOS RCA 22DE4 tubes) opens up a wider range of replacement options for “tube rolling,” a common practice in the world of tube amplifiers to tailor the sound signature to personal taste.

All internal wiring is hand-built point-to-point.

Three headphone outputs, three impedance ranges

One of the frequent criticisms of 300B headphone amplifiers concerns their difficulty with sensitive IEMs: too much background noise, too much available power, and insufficient precision in volume control. The MK3 addresses this issue with three separate outputs, each calibrated for a different use.

The balanced 4-pin Neutrik XLR output delivers up to 6,500 mW per channel. It is the main output, designed for planar magnetic headphones and high-impedance models that demand current. The 6.35 mm jack output provides 6,000 mW per channel in single-ended mode. The 4.4 mm Pentaconn output, capped at 1,600 mW per channel, is specifically optimized for IEMs: suitable level, reduced noise. This is rare on a 300B amplifier, and one of the significant new features of this generation.

A three-position impedance selector (Low: 8-65 Ω, Medium: 65-300 Ω, High: 300-600 Ω) allows the output load to be matched to the headphones in use. Frequency response extends from 12 Hz to 35 kHz (±3 dB), signal-to-noise ratio is rated at 100 dB (A), and total harmonic distortion remains below 1% at 1 kHz.

A speaker amplifier too

The HA-300 MK3 is not just a headphone amplifier. Its rear speaker terminals deliver 2 × 8 W in Class A, with a frequency response of 10 Hz to 35 kHz and a signal-to-noise ratio of 102 dB (A). This is modest in absolute terms, but sufficient to drive efficient compact speakers in an office or modestly sized room. Supported impedance ranges from 4 to 8 Ω. For those who alternate between headphone and speaker listening, this dual use avoids multiplying components.

Selected components and hybrid volume control

The choice of passive components says a great deal about the MK3’s positioning. The coupling capacitors are DUELUND models, made in Denmark and known in the tube amplification world for their low distortion and transparency. The tube sockets are gold-plated (rather than ceramic with gold-plated pins as on previous generations), improving conductivity, contact stability and durability.

Volume control combines two technologies: a JRC MUSES 72320 chip (high-fidelity electronic control, with low noise and low distortion) paired with a 41-step ALPS attenuator. This hybrid solution aims for the precision of digital adjustment with the smooth progression of a stepped potentiometer.

A design refined in every detail

Compared with the MK2, the finish moves to a sandblasted treatment that is more resistant to scratches and fingerprints than conventional brushed metal. The transformer cover has been streamlined: the decorative aluminum plates have been removed in favor of a more understated design that promotes heat dissipation. The tube protection cage adopts a new “family” design with a plug-in structure, replacing the former metal wire grille. This makes tube installation and replacement easier. The nameplate features a textured relief, and the tube rings have been reworked. Two front-panel VU meters provide a visual reference while listening. A 60-second delay with mute on power-up protects the circuit and headphones while the tubes reach operating conditions.

For inputs, the MK3 accepts one balanced XLR source and one RCA source, with input impedances of 12.5 kΩ (XLR) and 25 kΩ (RCA). There is no line output: this is a pure amplifier, not a preamplifier. There is also no remote control, meaning you need to get up to adjust the volume when listening through speakers.

Technical specifications

Architecture and design

• Type: tube amplifier for headphones and speakers
• Topology: single-ended Class A with 300B triodes
• Design: dual-chassis with separate power supply
• Wiring: hand-made point-to-point
• Power stage: 300B
• Voltage stage: regulated, low-noise
• Start-up delay: 60 seconds
• Power supply: enhanced circuit with improved isolation and reduced interference
  • Secure aviation-type connector

Audiophile components

• Wide-band EI output transformers (3rd generation)
• Toroidal power transformer (3rd generation)
• DUELUND coupling capacitors (Denmark)
• Volume control
  • JRC MUSES 72320 chip
  • 41-step ALPS attenuator
• Gold-plated tube sockets
• Selection of matched tubes with 48-hour factory burn-in

Included tubes

• 2 × Genalex Gold Lion PX300B: power amplification
• 2 × JJ 6SN7: voltage amplification
• 2 × JJ GZ34 / 5AR4: rectification
• Compatible with many equivalent tubes for sound customization (tube rolling)

Headphone output

• Power
  • Balanced 4-pin XLR: 6500 mW + 6500 mW
  • 6.35 mm jack: 6000 mW + 6000 mW
  • Balanced 4.4 mm Pentaconn: 1600 mW + 1600 mW (IEM-optimized)
• Frequency response: 12 Hz – 35 kHz (±3 dB)
• Total harmonic distortion: less than 1% (1 kHz, 1500 mW)
• Signal-to-noise ratio: 100 dB (A-weighted)
• Input sensitivity: 250 mV – 1200 mV
• Impedance ranges
  • Low: 8 – 65 Ω
  • Medium: 65 – 300 Ω
  • High: 300 – 600 Ω
• Headphone impedance selector: High / Medium / Low

Speaker output

• Power: 8 W + 8 W
• Amplification class: Class A
• Frequency response: 10 Hz – 35 kHz (±3 dB)
• Total harmonic distortion: less than 1% (1 kHz, 3 W)
• Signal-to-noise ratio: 102 dB (A-weighted)
• Compatible impedance: 4 – 8 Ω

Connectivity

• 1 × stereo RCA input
• 1 × balanced stereo XLR input
• 1 × 6.35 mm jack headphone output
• 1 × balanced 4.4 mm Pentaconn headphone output
• 1 × 4-pin XLR headphone output
• 1 × pair of speaker binding posts

Design and manufacturing

• Sleek, modern industrial design
• Premium sandblasted finish
• Redesigned tube protection cage
• Premium details: textured nameplate, improved tube rings
• Dual front-panel VU meters

Dimensions and weight

• Amplifier: 286 × 368 × 205 mm – 16.8 kg
• Power supply: 159 × 345 × 205 mm – 10 kg

Power supply

• Consumption: 160 W maximum
• Voltage
  • 220 – 240 V: T1.6A L250V fuse
  • 100 – 120 V: T3.15A L250V fuse
• 300B fuse: T100 mA E250V

Operating conditions

• Temperature: 0 °C to 40 °C
• Humidity: 20% to 80%