Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier
Cayin HA-300MK2 - Class A tube headphone amplifier

Cayin HA-300MK2 - Class A tube headphone amplifier

CHF 4,399.00
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Delivery time approx. 2 weeks

Test products at home - free of charge and for up to one week

The new flagship has landed!

The Cayin HA-300MK2 is finally here. Like its predecessor, the HA-300MK2 is a transformer-coupled Class A headphone and speaker single-ended
triode amplifier (SETA). It uses a matched pair of 300B Direct Heated Triode as output tubes and a matched pair of 6SN7 as driver tubes.

The tube amplification circuit is single-ended, which is why it's called SETA, and then connects to a pair of output transformers for single-ended headphones, XLR-4 and 4.4mm balanced headphone output, and a set of speaker terminals.

The irresistible directly heated triode 300B

Cayin HA-300MKII

Cayin HA-300MKII

Many tube enthusiasts consider the Directed Heated Triode (DHT) to be the vacuum tube holy grail for audio applications. DHT refers to triode tubes that use the cathode as a filament and heat the cathode directly during operation.

They can be considered a minimal amplification variant and have a large following, especially in Japanese and Japanese Chinese audiophile community.

There is a long list of vacuum tubes that belong to this family, but for modern audio applications the most commonly used DHT's are the 45, 2A3, 300B, 845 and 211, with the 300B being probably the best known and most sought after DHT in the audiophile community is.

The 300B offers attractive sound characteristics that come very close to an audiophile's dream. It has a distinctive, full-bodied midrange that's harmonically rich with detail that brings out the best in an acoustic instrument, and the holographic presence that makes the singers (or the band) appear to be standing right in front of you.

Technically, the 300B offers very high linearity in gain. This is probably the natural presentation and excellent low-level detail restoring presence that brings us closer to the music.

Cayin uses a matched pair of Gold Lion Genelex PX300B as the output tube for HA-300MK2. This is a low-noise audio triode that offers very good frequency extension with a natural, sensitive and realistic sound signature. This tube is considered by many 300B users to be an excellent upgrade tube and the best 300B tube for "mere mortals".

SETA, the purists' "One Way Ticket"

Cayin HA-300MKII

The Single-Ended Triode Amplifier (SETA) is a vacuum tube-based design that uses one triode tube per channel to generate the output without splitting the plus/minus portions of the signal in each channel.

In contrast, a push/pull amplifier, which uses a pair (or more) tubes, splits the plus/minus portions of the music signal and then
puts them back together to produce the full music wave in each channel form.

The perceived high sound quality is mainly due to the simplicity and minimalist approach of the circuits involved. One SET connoisseur describes it as "Zen simplicity to reflect the complexity of the music. Less is more."

Cayin recognized the beauty of SETA and put a lot of time and effort into developing
dozens of SETAs in our history. HA-300 and HA-300MK2 use the same 2-stage single-ended amplification with 6SN7 as driver tube. It amplifies the input signal to the appropriate level so that the 300B output tube performs its second stage amplification in a very linear state. Simply put, the driver tube amplifies the single voltage while the output tubes amplify the current.

Cayin always uses 6SN7 as driver tube when we use 300B as output tube. Chris Marten called this combination "legendary in audiophile circles" in his HA-300 review (HiFi+ July 2018, issue 161, pages 69-72).

For the implementation of the HA-300MK2, Cayin uses a matched pair of Tung-Sol 6SN7GTB as driver tubes for much the same reason as Genalex Gold Lion PX300B. This is a super linear, low noise, powerful, very reliable and natural sounding SET amplification driver tube.

Impedance-matched headphone outputs

Cayin HA-300MKII

Cayin HA-300MKII

A very useful feature of the Cayin tube amp is the impedance matched
matched headphone output. The HA-300 offers three headphone impedance settings and the amplifier optimizes its output to handle the headphone load.

Headphone load according to the specified headphone impedance

Each impedance-matched output is an independent secondary winding of the output transformers. The impedance settings are:

Recommended for target impedance (XLR4 and 4.4mm)

  • Low (L): 8Ω~64Ω 32Ω
  • Medium (M): 65Ω-250Ω 64Ω
  • High (H): 251Ω~600Ω 300Ω


The matched headphone impedance should produce a natural sound with well-defined
bass response. This is our recommended starting point, but feel free to experiment with the settings.

Back to the transformer

To sum up, the HA-300B's output transformers are extremely complicated because we need a pair of multi-wound output transformers designed for three headphone outputs (6.35mm, 4.4mm, XLR4) on the primary winding, and three impedance matched Headphone outputs and a set of speaker outputs on the secondary winding are responsible.


The transformer plays an important role in a transformer-coupled tube amplifier. Design and implementation of transformers is an important part of our product tuning. The choice of transformer core, the specification of the copper wire in the various parts of the winding, and the winding instruction all affect the performance and sonic signature of our product.

This is a critical core competency that maximizes our product development capability, extends our product lifecycle, and improves our operational efficiencies.

Given the scale of Cayin's work and dedication to building quality tube amps for our customers, Cayin bit the bullet and invested in a small transformer factory in our facilities.

We design and wind all of our tube amp power supply and output transformers ourselves. This gives the R&D department complete freedom in determining the winding instructions for our products and gives us full control over the material and craftsmanship of the transformers our tube amps.


Tube regulated external power supply

The HA-300MK2's power supply uses a custom-made toroidal transformer. This is a special circuit to power different gain stages and we used 4pcs NOS RCA 22DE4 rectifier tubes to convert the incoming power source to DC. This results in clean power with minimal interference to the amplifier circuit.

The NOS RCA 22DE4 are one of the best versions of the 22DE4 tube and when used as a rectifier tube in the HA-300MK2 they can easily be used for 5 to 10 years. The four 22DE4 work independently. If we're swapping out a 22DE4 rectifier tube, we can do it per piece, without the need for a matching process.

Design and properties

  • Single-ended direct-heated triode design, brings the charm of tubes with natural and realistic music reproduction.
  • Driver Tube: Matched pair of Tung-Sol 6SN7GTB
  • Output tube: matched pair of Genalex PX300B
  • Rectifier tube: 4 pieces NOS RCA 22DE4
  • Supports balanced (XLR) and unbalanced (RCA) input, balanced input is transformed to unbalanced by a pair of input transformers.
  • The output of the 300B features a pair of specially designed and high quality EI output transformers for speakers, unbalanced (6.35mm) or balanced (4-pin XLR and 4.4mm) headphone output.
  • Three impedance-matched headphone outputs (L, M, and H) are available to allow the HA-300MK2 to satisfactorily handle a variety of headphones.
  • Powerful headphone output that also accommodates demanding headphones with plenty of headroom.
  • Custom-made silica gel shock absorber acts as an anti-shock buffer between critical tube components, chassis main frame and tube socket, effectively removing the 300B DHT's microphonics and ensuring smooth and realistic reproduction of sensitive headphones.
  • Minimization of interference through reinforced shielding of the transformers, effective circuit layout and optimized circuit design
  • 60-second start-up delay circuit to improve circuit protection and minimize pops during start-up.
  • A set of speaker terminals as an alternative output, can be used as an integrated speaker amplifier with 8 watts per channel and Class A output.
  • An external power supply ensures pure and smooth power supply to the amplifier circuitry with minimal interference.
  • High-quality toroidal transformer developed and manufactured in-house, as well as EI output transformers.
  • High voltage rectification with a set of four NOS RCA 22DE4 tubes.
  • Two box design with multi-stage tube-regulated power supply effectively reduces signal amplification interference by independently regulated power supply for voltage amplification circuit. Optimizes the power supply for all circuits and greatly improves audio performance.
  • Point-to-point wiring to ensure the shortest signal path, achieving transparency and refinement of audio performance.
  • High-precision electronic volume control JRC MUSES72320V with 41 levels
  • ALPS potentiometer for low-noise and precise volume control
  • High-quality MultiCap coupling capacitor improves resolution and sound.
  • High quality shielded silver-plated cable for internal wiring, minimizes interference during internal transmission.
  • Beautifully designed and finished VU meter
  • Lock On quick-release fasteners made from aerospace grade copper with silver-plated Teflon
  • Cable for connecting the external power supply.
  • Removable vacuum tube shielding cage, easy to remove and install.


Technical data

Cayin HA-300MKII

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