Classic. Modern. Solid-State.
The RU9 provides three distinct timbre modes: Classic, Modern, and Solid-State.
- Classic Tube Mode delivers a warm, nostalgic sonic character — the traditional tube sound cherished by audio purists.
- Modern Tube Mode offers a sweeter, clearer, and more refined tube presentation. It provides a quieter background and cleaner harmonics, while maintaining the musical warmth of tubes.
- Solid-State Mode is ideal when you want to hear the music in its pure, unaltered form. It delivers neutral tonality, fast transients, and highly accurate reproduction.
NuTube 6P1 Implementation
The tube stage features a three-stage amplification design, incorporating six Toshiba 2SK209 audio-grade JFETs and a hand-matched KORG NuTube 6P1 dual triode. Both the single-ended and balanced outputs of the RU9 are capable of delivering rich tube tonality.
Premium Components
Drawing on years of expertise in high-end audio, Cayin has engineered the RU9 using top-tier components.
The RU9 features dual AK4493SEQ DAC chips, each running in mono mode. By decoding the left and right channels independently, crosstalk is reduced and channel separation is greatly improved.
Powered by the latest-generation XMOS XU316 USB processor, the RU9 supports native DSD512 and 32-bit/768kHz PCM playback. The decoded signal is then driven through a four-channel balanced headphone amplifier, utilizing dual ultra-low-noise, ultra-low-distortion OPA1662 op-amps alongside four Nexperia audio power transistors for robust and precise amplification.
- Dual AK4493SEQ DACs with upgraded VELVET SOUND™ technology
- Korg NuTube 6P1 for warm, analog tube character
- Three Timbre Modes: Classic Tube, Modern Tube, Solid-State
- Supports PCM up to 32bit/768kHz and Native DSD512 decoding
- Bluetooth 5.1 with LDAC, aptX HD, and aptX LL
- USB DAC functionality powered by XMOS XU316 16-core processor
- Balanced (4.4mm) and single-ended (3.5mm) headphone outputs
- Up to 1W output in Hyper Mode
- Four-channel JRC NJW1195A electronic volume control
- Magnetic back panel + premium leather case included
RU9 Product Information
Tube: KORG Nutube 6P1
DAC Chip: AK4493SEQ × 2
Charge Port: USB Type-C (QC3.0/PD2.0)
USB Processor: XMOS XU316
Bluetooth Processor: QCC5125
Battery: 2000mAh, 3.85V 7.7Wh Lithium Polymer Battery
Dimension: 100×70×15 (mm)
Weight: 150g (±5g)
RU9 Battery and Duration
3.5mm PO/LO
Solid-state: 4.7 hrs.
Vacuum Tube: 3.5 hrs.
4.4mm PO/LO
Solid-state: 4.3 hrs.
Vacuum Tube: 3.1 hrs.
Charging Condition: QC3.0 / PD2.0
Charging Time: 1.3 hr.
Note:
Test conditions are based on pure battery mode (source playing 44.1kHz audio, 32Ω load, high gain, volume at level 30).
Since battery life is affected by factors such as device status and usage environment, the data provided is for reference only.
RU9 3.5mm PO Output
Specification | Solid-State Timbre | Classic Tube Timbre | Modern Tube Timbre
Output Power
310mW+310mW (BAT)
420mW+420mW (DC)
(RL=32Ω, 1kHz, THD+N≤0.5%)
310mW+310mW (BAT)
420mW+420mW (DC)
(RL=32Ω, 1kHz, THD+N≤3.1%)
310mW+310mW (BAT)
420mW+420mW (DC)
(RL=32Ω, 1kHz, THD+N≤1%)
440mW+440mW (BAT)
610mW+610mW (DC)
(RL=16Ω, 1kHz, THD+N≤0.5%)
440mW+440mW (BAT)
610mW+610mW (DC)
(RL=16Ω, 1kHz, THD+N≤3.1%)
440mW+440mW (BAT)
610mW+610mW (DC)
(RL=16Ω, 1kHz, THD+N≤1%)
Frequency Response (±0.5dB, Fs=192kHz, Sharp): 20Hz-32kHz | 20Hz-22kHz | 20Hz-32kHz
THD+N (1kHz, Fs=192kHz, A-weight, 20Hz-20kHz, Output: 0.5V): ≤0.008% | ≤3.0% | ≤0.6%
Dynamic Range (1kHz, A-weight, 20Hz-20kHz): ≥119dB | ≥105dB | ≥115dB
SNR (1kHz, A-weight, 20Hz-20kHz): ≥118dB | ≥104dB | ≥114dB
Channel Separation (RL=32Ω, 1kHz, A-weight): ≥76dB | ≥68dB | ≥76dB
Gain: H: 0dB / M: -6dB / L: -12dB (Selectable)
Output Impedance: 0.5Ω
RU9 4.4mm PO Output
Specification | Solid-State Timbre | Classic Tube Timbre | Modern Tube Timbre
Output Power
620mW+620mW (BAT)
1000mW+1000mW (DC)
(RL=32Ω, 1kHz, THD+N≤0.5%)
620mW+620mW (BAT)
1000mW+1000mW (DC)
(RL=32Ω, 1kHz, THD+N≤3.1%)
620mW+620mW (BAT)
1000mW+1000mW (DC)
(RL=32Ω, 1kHz, THD+N≤1%)
730mW+730mW (BAT)
1170mW+1170mW (DC)
(RL=16Ω, 1kHz, THD+N≤0.5%)
730mW+730mW (BAT)
1170mW+1170mW (DC)
(RL=16Ω, 1kHz, THD+N≤3.1%)
730mW+730mW (BAT)
1170mW+1170mW (DC)
(RL=16Ω, 1kHz, THD+N≤1%)
Frequency Response (±0.5dB, Fs=192kHz, Sharp): 20Hz-32kHz | 20Hz-22kHz | 20Hz-32kHz
THD+N (1kHz, Fs=192kHz, A-weight, 20Hz-20kHz, Output: 0.5V): ≤0.008% | ≤3.0% | ≤0.6%
Dynamic Range (1kHz, A-weight, 20Hz-20kHz): ≥119dB | ≥105dB | ≥115dB
SNR (1kHz, A-weight, 20Hz-20kHz): ≥118dB | ≥104dB | ≥114dB
Channel Separation (RL=32Ω, 1kHz, A-weight): ≥105dB | ≥98dB | ≥105dB
Gain: H: 0dB / M: -6dB / L: -12dB (Selectable)
Output Impedance: 1.0Ω
RU9 Digital Input and Output
Mode: UAC2.0/1.0 (Selectable)
USB Audio In
Windows: Windows 10 or later (Cayin USB Audio Driver may be required)
MAC OSx: Driver-free
Android: Driver-free
iOS: Driver-free
Audio Format: PCM: 16-32Bit, 44.1kHz-768kHz (UAC2.0); DSD: Native DSD64-512, DoP64-256 (UAC2.0)
Bluetooth In
Codec Support: LDAC, aptX HD, aptX LL, aptX, AAC, SBC
Bluetooth Version: BT v5.1
S/PDIF In
Audio Format: PCM: 16-24Bit, 44.1kHz-192kHz
Input Connector: 3.5mm Port (shared with S/PDIF Out)
S/PDIF Out
Audio Format: PCM: 16-24Bit, 44.1kHz-192kHz
Input Connector: 3.5mm Port (shared with S/PDIF In)
Note:
The above specifications are based on engineering sample data. Actual performance may vary due to firmware updates or hardware revisions without prior notice.
Triple Power Supply Options
The built-in 2000 mAh lithium battery provides up to 4.7 hours of playback on a single charge. The RU9 can also draw direct USB power from connected devices, bypassing the battery, or operate from an external DC power supply for improved output performance. It fully supports QC and PD fast-charging standards.
Hyper Mode
Designed specifically for use with headphones when powered by DC, Hyper Mode increases the static operating current and voltage to boost overall audio performance. This mode delivers powerful output, reaching 1000 mW at 32 Ω.
Versatile Connectivity
The RU9 works effortlessly with smartphones, computers, digital audio players, tablets et consoles de jeu.
A magnetic rear panel enables easy attachment to smartphones, and the device supports both UAC1.0 (driverless) and UAC2.0 USB audio modes.
Vibration Isolation System
To protect the NuTube vacuum tube from microphonics, Cayin designed a custom anti-vibration structure featuring a silicone housing on a flexible FPC PCB and a pin-supported vertical suspension system, effectively reducing unwanted vibrations.
Thoughtful Design Details
The RU9 includes a 0.96" color display with adjustable brightness, a molette de volume moletée, and a side-mounted indicator light that shows charging status and sample rate/format.
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