Cayin RU9

The Cayin RU9 redefines portable audio by combining vacuum tube warmth with modern high-resolution DAC performance in a compact, pocket-sized device. Featuring the groundbreaking Korg NuTube 6P1 vacuum tube, dual AK4493SEQ DAC chips, and a powerful balanced amplifier stage, the RU9 delivers a rich, immersive listening experience typically reserved for desktop systems.

Designed for audiophiles who want uncompromised sound on the go, the RU9 offers versatile connectivity, multiple sound signatures, and powerful output—making it the perfect companion for smartphones, laptops, tablets, and digital audio players.

Tube Warmth, Anywhere You Go

At the heart of the RU9 lies the Korg NuTube 6P1 vacuum tube, bringing the beloved warmth, harmonic richness, and smooth tonal character of traditional tube amplifiers to a portable DAC/amp.

Cayin integrates the tube into a three-stage amplification architecture, combining six Toshiba 2SK209 audio-grade JFETs with a carefully matched dual-triode tube circuit. This design delivers authentic tube timbre with enhanced stability, low noise, and impressive dynamic range.

Both 3.5mm single-ended and 4.4mm balanced outputs benefit from this tube amplification, providing a lush and engaging sound signature for headphones and IEMs.

Three Distinct Sound Signatures

RU9 offers three selectable timbre modes, allowing listeners to tailor the sound to their preferences or music style.

Classic Mode
Delivers the nostalgic warmth and smooth harmonic character associated with traditional tube amplifiers.

Modern Mode
A refined tube signature that retains warmth while providing a cleaner, more detailed presentation with a quieter background.

Solid-State Mode
Disables the tube stage for a neutral, fast, and highly accurate sound reproduction with precise transients and clarity.

Dual AKM DAC Performance

The RU9 uses dual AK4493SEQ DAC chips, each operating in mono mode for the left and right channels. This design significantly improves channel separation and reduces crosstalk, producing a wider soundstage and more precise imaging.

Powered by the XMOS XU316 USB processor, RU9 supports native DSD512 and 32-bit / 768kHz PCM playback, ensuring exceptional high-resolution audio performance.

Powerful Balanced Amplification

The DAC signal is amplified through a four-channel balanced headphone amplifier circuit using dual ultra-low noise OPA1662 op-amps and Nexperia audio power transistors. This configuration delivers outstanding control, clarity, and dynamic power across a wide range of headphones.

In Hyper Mode, the RU9 can output up to 1000mW at 32Ω, providing enough power to drive demanding headphones with authority.

Triple Power Supply System

The RU9 is designed for flexible use with three different power supply options:

• Internal Battery Mode – Built-in 2000mAh lithium battery provides up to 4.7 hours of playback.

• USB Power Mode – Draws power directly from connected devices while bypassing the internal battery.

• External DC Power Mode – Enables maximum performance and output power for demanding headphones.

The device also supports QC and PD fast charging standards for quick recharging.

Designed for Modern Portability

RU9 features a magnetic rear panel that allows easy attachment to smartphones, creating a clean and compact portable audio setup.

Dual USB-C ports provide flexible connectivity, while physical playback controls allow convenient operation without reaching for your phone.

With support for UAC1.0 (driverless) and UAC2.0 modes, RU9 works seamlessly with smartphones, computers, tablets, digital audio players, and gaming consoles.