Cayin RU9 | Vacuum Tube Portable DAC and Amp
Cayin Expands Their Legacy of Innovation by Introducing RU9, a Pocket-Sized DAC/Amp Featuring a Korg NuTube 6P1 Vacuum Tube
- First portable DAC/Amp to implement a Korg NuTube 6P1 Tube
- High-performance dual AK4493SEQ DACs
- Three timbre options: Classic, Modern and Solid-State
- Magnetic back design allows smartphone attachment
- 3.5mm SE + 4.4mm Balanced phone and line outputs
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Bloom's Take Cayin’s RU9 isn’t just another DAC dongle, it’s a bold reimagining of what portable audio can be. Marrying the richness of tube sound with the convenience of MagSafe, Cayin provides a compact unit that delivers serious desktop-quality sonics from your pocket. With three selectable sound modes: Classic, Modern, and Solid-State, the RU9 adapts to your mood and gear, offering anything from clinical precision to analog warmth. Its tuning is natural and relaxed, allowing your IEMs to shine without imposing its own character, while still delivering a wide soundstage and refined detail. Whether you’re pairing it with a $100 IEM or a flagship CIEM, the RU9 scales effortlessly and never feels out of place. Add in thoughtful design touches like dual USB-C ports, physical playback controls, and the sheer novelty of MagSafe mounting, and you’ve got one of the most well-rounded portable audio tools we’ve ever tested. The RU9 isn’t just convenient, it’s a joy to use and a true standout in the portable DAC/Amp space. |
Tube Warmth On-the-Go
The Cayin RU9 is the latest addition to the RU series. It is a compact, portable DAC and amp that brings the classic tube sound to your mobile audio experience. Featuring the Korg NuTube 6P1 vacuum tube, the RU9 offers audiophiles a unique blend of classic and modern sound signatures.
Classic. Modern. Solid-State.
The RU9 offers users three distinct timbre options: Classic, Modern and Solid-State. As the name implies, the Classic tube mode delivers a warm, nostalgic sonic flavor - the classic tube sound.
The Modern tube timbre yields a sweet, clear and delicate modern tube sound signature. It's harmonically cleaner, offering a quieter background while preserving the warmth of tubes.
The Solid-State mode is ideal for listening to music with its original, uncolored character. It delivers neutral tonality, fast transients and highly accurate audio reproduction.
NuTube 6P1 Application
The tube circuit adopts a three-stage amplification architecture, consisting of 6 Toshiba 2SK209 audio-specific junction field effect transistors (JFETs) and a manually tested paired KORG Nature 6P1 dual triode tube. Both the single-ended and balanced ports on the RU9 can output rich tube sound.
Premium Components
With years of experience crafting high-end audio equipment, Cayin has applied their expertise to engineer the RU9 with exceptional components. RU9 is equipped with dual Equipped with dual AK4493SEQ DACs, each operating in mono mode. The Left and right channels are decoded separately for lower crosstalk and better channel separation.
Employing the latest generation XMOS XU316 USB processor, RU9 supports native DSD512 and 32bit/768kHz PCM signals. The processed signal is then amplified by a four-channel balanced headphone amplifier circuit. It uses dual ultra-low noise and ultra-low distortion OPA1662 OPAMPs with four Nexperia audio power tubes.
Additional Features
Triple Power Supply Modes
The built-in 2000mAh lithium battery offers up to 4.7 hours of playback on a single charge. The RU9 also supports USB power directly from connected devices (bypassing the battery), as well as an external DC power supply for enhanced output performance. It is fully compatible with QC and PD fast charging standards.
Hyper Mode
A specialized feature designed for headphone usage under DC power supply. It increases static operating current and voltage for enhanced audio performance. Producing a strong output, it reaches 1000mW at 32Ω impedance load.
Versatile Use Scenarios
The RU9 is compatible with smartphones, computers, digital audio players, tablets and gaming consoles. A magnetic rear panel allows seamless attachment to smartphones. RU9 supports UAC1.0 (driverless) and UAC2.0 modes.
Vibration Isolation
A custom anti-vibration system was designed for the NuTube vacuum tube. It features silicon housing on a FPC flexible PCB and a pin-supported vertical suspension system to eliminate microphonics.
Thoughtful Details
RU9 features a 0.96" color display with adjustable brightness, knurled volume knob and side-mounted indicator light for charging + sample rate/format display.
Specifications
- Material: CNC-machined unibody metal chassis
- DAC: (2x) AK4493SEQ
- Decoding: PCM up to 768kHz/32bit, DSD512
- Bluetooth: v5.1 with LDAC, aptX HD and aptX LL support
- Bluetooth Chip: Qualcomm QCC5125
- Battery: 2000mAh, polymer lithium-ion
- Connectivity: USB-C input
- Weight: 5oz
- Dimensions: 3.9" x 2.7" x 0.6"
In the Box
- Cayin RU9 DAC and amp
- Leather case
- L-shaped USB cable
