RU9
The Evolution of Portable Tube Audio
The Cayin RU9 combines the convenience of a premium portable DAC/headphone amplifier with the unmistakable character of genuine tube sound. Featuring Cayin's fifth-generation tube implementation and the acclaimed KORG Nutube 6P1, the RU9 delivers a unique listening experience that allows users to switch seamlessly between two distinct tube signatures and a highly transparent solid-state mode.
Unlike conventional portable DACs, the RU9 offers its Triple Timbre technology across both 3.5mm single-ended and 4.4mm balanced headphone and line outputs, allowing listeners to tailor the sound to their headphones, music and personal preferences.
Triple Timbre Technology
At the heart of the RU9 is a sophisticated analogue stage built around six Toshiba 2SK209 audio-grade JFETs and a carefully selected KORG Nutube 6P1 dual-triode vacuum tube.
The JFET input stage provides ultra-low-noise buffering, while the Nutube stage delivers voltage amplification and creates the RU9's distinctive tube character. A dedicated JFET output buffer enhances current delivery, ensuring excellent drive capability and maintaining the benefits of tube operation without sacrificing control or dynamics.
Classic Tube Mode
Designed to capture the traditional character of vintage valve amplifiers, Classic Tube mode employs local feedback throughout the amplification stages without a large global feedback loop. The result is a rich, organic presentation with enhanced warmth, harmonic texture and the unmistakable character associated with classic tube designs.
Modern Tube Mode
By incorporating a carefully engineered global negative feedback network, Modern Tube mode reduces distortion and noise while preserving the musicality of the Nutube stage. The result is a cleaner, more refined presentation with improved clarity, detail and extension.
Solid-State Mode
For listeners seeking maximum transparency, the RU9's solid-state circuit bypasses the tube stage entirely. Precision-tuned op-amp circuitry delivers fast transient response, exceptional resolution and a highly neutral tonal balance.
Advanced Anti-Microphonic Design
Vacuum tubes are traditionally susceptible to vibration-induced noise, particularly in portable applications. To overcome this challenge, Cayin developed a dedicated anti-vibration system for the Nutube 6P1.
A flexible FPC mounting system, custom silicone damping sleeve and suspended pin structure work together to minimise mechanical resonance and effectively eliminate microphonic interference, ensuring stable tube performance wherever you listen.
Hyper Mode Performance Enhancement
When operating in DC Mode, the RU9 automatically activates Hyper Mode. This advanced operating state increases amplifier bias current and operating voltage, unlocking even greater sonic performance.
Hyper Mode delivers improved dynamic impact, enhanced transparency, greater instrument separation and a more expansive soundstage, allowing the RU9 to perform at its full potential.
Flagship XMOS USB Processing
The latest-generation XMOS XU316 USB controller provides exceptional processing power through its advanced 16-core, 32-bit architecture.
Supporting native DSD512 and PCM playback up to 768kHz/32-bit, the XU316 ensures accurate high-resolution audio decoding while maintaining excellent compatibility with modern operating systems and playback devices.
Dual AK4493SEQ DAC Architecture
Two AK4493SEQ DAC chips operate independently in dedicated mono mode, creating a fully differential signal path.
Separate decoding for the left and right channels reduces crosstalk, improves channel separation and enhances overall soundstage precision, revealing greater detail and spatial accuracy within recordings.
Fully Balanced Amplification Stage
The analogue output stage features a fully balanced four-channel amplifier architecture powered by dual Texas Instruments OPA1662 operational amplifiers and four Nexperia output transistors.
This carefully engineered design improves signal integrity, reduces external interference and provides stable, powerful headphone drive across a wide range of headphones and in-ear monitors.
Flexible Power Architecture
The RU9 offers three operating modes to accommodate different listening scenarios and performance requirements.
Dongle Mode
Compact, efficient operation powered directly via USB.
Battery Mode
Utilises the internal battery to reduce the power burden on connected mobile devices while maintaining excellent audio performance.
DC Mode
Direct external power delivery bypasses battery limitations and automatically activates Hyper Mode, providing maximum output capability and ultimate sonic performance.
Support for QC3.0 and PD2.0 fast charging ensures convenient charging and minimal downtime.
Designed for Modern Mobile Listening
The RU9's integrated magnetic attachment system allows it to snap securely onto compatible smartphones and tablets, creating a compact and elegant portable audio solution.
Included in the package is a custom magnetic PU leather case with integrated magnetic backing, along with a high-quality shielded L-shaped USB cable designed to minimise signal loss while maintaining a clean portable setup.
Premium Craftsmanship
The chassis is precision-machined from a single block of aluminium, providing exceptional rigidity, durability and heat dissipation.
Cayin's advanced thermal management design helps maintain stable performance during extended listening sessions while preserving the RU9's remarkably compact footprint.
Thoughtful User Experience
A bright 0.96-inch display provides clear access to playback information and settings, while the knurled volume wheel and tactile control buttons offer precise and satisfying operation.
Multi-colour status indicators display charging information and playback sample rates at a glance, while the laser-machined Nutube viewing window reveals the warm glow of the tube during operation. Carefully designed to minimise electromagnetic interference while showcasing the unique character of the Nutube, it adds a visual element that perfectly complements the RU9's engaging musical performance.
