Features Gen5 Nutube 6P1 Vacuum Tube For Exceptional Audio Performance

Cayin C9ii features the KORG Nutube 6P1, a compact and energy-efficient double DHT vacuum tube developed in 2015. Leveraging Vacuum Fluorescent Display (VFD) technology, the Nutube delivers warm, tube-like sound while maintaining a slim design and long lifespan. Despite its low heat and power consumption, the Nutube's sensitivity to microphonics posed challenges for portability. Cayin addressed this with a custom-engineered Suspended Installation System featuring silicon housing, shock absorption, and a flexible circuit board, minimizing microphonics and enhancing performance for the portable headphone amplifier.

Equipped With Vacuum Tube Circuit With Fully Discrete JFET Buffering For Refined Sound

Cayin C9ii features a Gen5 Nutube 6P1 vacuum tube circuit combined with discrete JFET buffering and a high-performance constant current source. Its three-stage low-gain timbre circuit uses Nutube 6P1 tubes as low-gain voltage amplifiers for warm, tube-like sound. Stage 1 employs Toshiba 2SK209 JFETs for load driving. Stage 2 uses Nutube pairs for balanced voltage amplification. Stage 3 integrates additional JFETs for enhanced current driving. Users can switch between high and low anode voltages to adjust sound linearity and harmonic distortion. The dual tube timbre design offers "Modern" and "Classic" options, while a discrete solid-state timbre circuit ensures versatile and refined sound shaping.

Houses Adjustable Anode & Tube Timbre With Dual Amp Modes For Tailored Sound

Cayin C9ii offers exceptional sound customisation with adjustable anode voltage, dual tube timbre, and versatile dual amp modes. Users can fine-tune sound linearity and harmonic distortion with high and low anode voltage settings, while the dual tube timbre design provides distinct Modern and Classic options to suit various musical preferences. The amp modes include Class A for warm, smooth playback, Class AB for efficiency and dynamic range, and Hyper mode for maximum audio output and enhanced soundstage. Its three-stage Nutube circuit, featuring Nutube 6P1 tubes and 16 Toshiba 2SK209 JFETs, ensures steady current delivery and outstanding sound quality.

Utilises Three Different Tube Timbre Circuit For A Customised Music Listening Experience

Cayin C9ii offers three distinct timbre circuits: a classic tube timbre with independent local feedback and no large-loop NFB, resulting in higher harmonic distortion and a warm, rich sound reminiscent of traditional tube amplifiers. The modern tube timbre uses large-loop NFB across multiple stages for lower THD, delivering a cleaner, modern tube sound with reduced noise. Lastly, the solid-state timbre employs a single-ended Class A design for smooth, natural, and fatigue-free audio output.

Experience Five Different Sound Profiles With Five Distinctive Timbre Settings

The Negative Feedback (NFB) feature adds further customization with Local Feedback (ON) for richer harmonics and warmer bass, or Large-loop Feedback (OFF) for enhanced dynamics and spatiality. With dual input modes (Line Input or Pre-Amp Input), three amplification modes (Class A, Class AB, Hyper), and three timbre options, the C9ii offers unmatched flexibility to craft a sound profile for any genre or listening preference.

A Fully Symmetric Headphone Amplifier With Multi-Stage Amplification For High Performance

Cayin C9ii is a fully symmetric headphone amplifier with a four-channel differential circuit, enhancing performance, signal coherence, noise reduction, stereo imaging, and symmetry. It features a Symmetric JFET Differential Input Amplifier with eight ultra-low-noise JFETs (LSK489 and LSJ689) for consistent performance. The Symmetric BJT Push-Pull Differential Voltage Amplifier, using Toshiba audio-grade PNP transistors, ensures stable operation and optimal harmonic distribution. The final Symmetric BJT Push-Pull Parallel Current Amplifier employs high-power Nexperia bipolar transistors, offering excellent thermal stability, superior current handling, and improved load-driving capacity for compatibility with various headphones and IEMs.

Features JRC MUSES Series 2 For High-Precision Volume Control & Premium Quality Internal Wiring

Cayin C9ii features high-precision volume control using JRC MUSES72320V 2-channel analogue chips with 131 steps, ensuring optimal balance and low distortion in a fully differential circuit. The resistance-ladder design ensures excellent channel synchronization and minimal noise. Volume adjustments are electronically controlled, with an ALPS potentiometer used for physical sampling, offering precise control even at low levels. The amplifier includes a two-stage gain control (High/Low) for compatibility with various IEMs and headphones. For premium connectivity, the upgraded CS-44C4411 balanced cable features shielded OCC Litz conductors and twisted OFC wire, enhancing clarity, imaging, and reducing noise.

Powered By Direct Battery Power Supply With Replaceable Battery Design For Impressive Power Supply

Cayin C9ii is powered by four Samsung 35E 3400mAh 18650 batteries, providing a direct ±8.4V supply to the amplification circuit, eliminating the need for DC/DC regulation. This design ensures excellent transient current delivery for superior audio performance. Premium components, such as WIMA film capacitors, C0G-type MLCCs, Panasonic POSCAPs, and OS-CON capacitors, create a low-resistance, fast-responding power supply with enhanced noise filtering. The Samsung 35E batteries, known for high energy density and low internal resistance, improve headroom and transient response. The modular, tool-free battery tray features quick-release latches, self-locking mechanisms, and a secure SATA interface, also functioning as a standalone charger. The replaceable battery design allows users to experiment with different 18650 batteries to fine-tune sound quality.

Provides Effective Heat Dissipation With an Advanced Thermal Management System

Cayin C9ii features a thermal management system with high-conductivity graphite pads and CNC-machined heat sinks for efficient heat dissipation. The chassis, made from 6063-T6 aluminium alloy, offers excellent thermal conductivity (~200 W/m·K) and improved strength due to T6 heat treatment. The increased width (from 160mm to 165mm) allows for additional heat sinks on the side panels, ensuring even temperature distribution and minimizing heat-related performance issues for consistent operation.

Industrial Design With Exquisite Details & Dual Input/Output Options

Cayin C9ii is meticulously crafted with a high-precision CNC-machined chassis for an industrial design and exquisite metallic feel. The sides feature an elegant curved design with enhanced grip comfort while significantly increasing heat dissipation. It equips 4 LED battery indicators that display the battery capacity and the LED flashes as charging indicators when connected to a USB charger. It features mini handles on each side to protect the toggle switches from accidental bumps or damage. It embeds 2 display windows for Nutube VFD, while the iconic gold ring on the potentiometer of the C9 series features CNC mirror polishing and PVD gold plating techniques. C9ii features input and output options of 4.4mm Balanced and 3.5mm Single-ended. Single-ended input will convert to a Balanced audio signal internally to take full advantage of the high-current balanced headphone amplifier.