Cayin HA-6A MK2

Class A Tube Headphone Amplifier with External Power Supply, KT88 Output Stage and Triode / Ultra-Linear Operation

With the HA-6A MK2, Cayin has comprehensively refined one of its most versatile tube headphone amplifiers. The second generation retains the fundamental concept of the original HA-6A while introducing significant technical improvements: the power supply is now housed in a separate chassis, the output stage comes equipped with Genalex Gold Lion KT88 tubes as standard, and the circuitry has been optimised for higher output power, lower noise and even greater flexibility.

At its core, the HA-6A MK2 remains a classic analogue tube amplifier: a single-ended Class A circuit, output transformers, tube rectification and selectable Triode or Ultra-Linear operation allow the listener considerably more influence over the sonic character than a conventional headphone amplifier.

One Amplifier – Two Sonic Characters

A front-panel switch allows the HA-6A MK2 to operate in either Triode (TR) or Ultra-Linear (UL) mode. This changes not only the available output power but also the overall presentation of the amplifier.

Triode mode places greater emphasis on a smooth, organic and spatially dimensional presentation. Vocals and acoustic instruments in particular benefit from the natural texture and fluidity associated with a high-quality tube circuit.

Ultra-Linear mode, on the other hand, provides more power, control and dynamics. More demanding planar magnetic headphones in particular benefit from the additional authority and stronger drive.

KT88 Power Tubes and a Fully Tube-Rectified Power Supply

Inside the amplifier, two JJ 12AU7 / ECC82 tubes handle voltage amplification, while two Genalex Gold Lion KT88 tubes form the output stage. Even the high-voltage rectification is handled by tubes rather than solid-state components, using two JJ GZ34 / 5AR4 rectifier tubes in the separate power supply.

Cayin does not restrict the HA-6A MK2 to its factory-installed tube set. The output stage supports a wide variety of compatible tubes including EL34, KT66, 6CA7, 6L6, KT77, KT88, 6550, KT90, KT120 and KT150. Various alternatives are also available for the rectifier and preamplifier tubes.

The HA-6A MK2 therefore offers exceptional scope for tube rolling. Simply changing the tubes allows the sound to be tuned from warm and smooth to more direct, dynamic and controlled, without having to replace the amplifier itself.

Separate Power Supply for a Quieter Signal Path

One of the most important changes compared with the original HA-6A is its two-chassis design. The power supply and amplifier circuitry are now housed in physically separate enclosures.

This keeps the sensitive audio circuitry away from transformers and the high currents of the power supply, reducing magnetic interference and helping the HA-6A MK2 achieve a remarkably low noise floor for such a powerful tube amplifier. Cayin specifies a signal-to-noise ratio of 104 dB (A-weighted) at the headphone output.

Up to 4.5 Watts per Channel

Despite its traditional tube topology, the HA-6A MK2 is by no means intended only for easy-to-drive dynamic headphones. Through the balanced 4-pin XLR output, it delivers up to 4,500 mW per channel in Ultra-Linear mode.

In addition, the amplifier features an unbalanced 6.35 mm headphone output and a balanced 4.4 mm Pentaconn output. The latter intentionally offers lower output power, extending the HA-6A MK2's versatility towards more sensitive headphones and in-ear monitors.

• 4-pin XLR: 2 × 4,500 mW (UL) / 2 × 3,000 mW (TR)
• 6.35 mm: 2 × 3,500 mW (UL) / 2 × 2,300 mW (TR)
• 4.4 mm Pentaconn: 2 × 1,000 mW (UL) / 2 × 650 mW (TR)

Impedance Matching from 8 to 600 Ohms

Output power tells only part of the story with a tube amplifier. Correctly matching the output transformer to the connected headphones is equally important.

For this purpose, the HA-6A MK2 offers three selectable impedance ranges:

• Low: 8–64 Ω
• Medium: 65–250 Ω
• High: 251–600 Ω

This allows the amplifier to accommodate everything from low-impedance planar magnetic headphones to traditional high-impedance dynamic models. The output transformers can therefore operate within a range appropriate for the connected load.

Now Also a Tube Preamplifier

The HA-6A MK2 is not limited to headphone listening. New compared with its predecessor is an RCA pre-out, allowing the Cayin to serve as a fully fledged analogue tube preamplifier.

It can therefore be paired with a separate power amplifier or active loudspeakers. The maximum preamplifier output voltage is 6 V, with a gain of 20 dB.

Balanced and Unbalanced Inputs

For connection to DACs, streamers and other analogue sources, the HA-6A MK2 provides both XLR and RCA inputs. On the output side, it covers all of the most common modern headphone connection standards.

• 1 × stereo XLR input
• 1 × stereo RCA input
• 1 × 4-pin XLR headphone output
• 1 × 4.4 mm Pentaconn headphone output
• 1 × 6.35 mm headphone output
• 1 × stereo RCA pre-out

A supplied remote control completes the package and is particularly useful when using the HA-6A MK2 as a preamplifier.

Cayin HA-6A MK2 – Highlights

• Single-ended Class A tube headphone amplifier
• Separate power supply chassis for reduced electromagnetic interference
• 2 × Genalex Gold Lion KT88 power tubes
• 2 × JJ 12AU7 / ECC82 preamplifier tubes
• 2 × JJ GZ34 / 5AR4 rectifier tubes
• Selectable Triode and Ultra-Linear operation
• Up to 4.5 W output power per channel via 4-pin XLR
• Three impedance ranges for headphones from 8 to 600 Ω
• 4-pin XLR, 4.4 mm Pentaconn and 6.35 mm headphone outputs
• XLR and RCA line inputs
• RCA preamplifier output
• Extensive tube rolling possibilities
• Remote control included

Technical Specifications