The Cayin RU7 is the new USB DAC dongle from the Asian firm and a brand new update to the best-selling RU6. It has a 4.4mm balanced output and the ability to decode All to DSD up to 256.

In addition, and although its size is compact, this small dongle is capable of reaching 400mWoutput power per balanced output and 160mW per standard 3.5mm output. 

If you want to rediscover the essence of portable audio, the RU7 is the best alternative.

The Cayin RU7 mounts a microminiaturized 1-bit DAC circuit intentionally designed from discrete components. It converts the digital signal into analog signal through a completely differentiated 4-channel DAC architecture. The 1-bit DAC circuit is a resistor network that will pass through a 3-level active LPF and then converted to a single-ended signal for volume adjustment.

In its amplifier section, this RU7 features dual parallel amplifiers, which provide a 4-channel high-power balanced driven output. The second amplifier is a unity gain parallel phase inverting amplifier, resulting in unparalleled output power:

• SE 3.5 mm, 160 mW at 32 Ohms
• Balanced 4.4 mm, 400 mW at 32 Ohms

The line output voltage is carefully selected to retain the greatest amount of detail and dynamics of the 1-bit DAC with the least noise and distortion; This allows you to connect the RU7 to a portable/desktop amplifier or home audio system and use it as a miniature DAC.

The discrete resistance network DAC circuit is very demanding on the integrity of the incoming data, we recommend users to keep the digital volume of the mobile phone at its maximum power to safeguard the quality of the digital audio signal.

When off-the-shelf analog volume options cannot meet the high precision, low noise and low power consumption requirements of RU7, a discrete resistance network self-volume control is developed. 

The Cayin RU7features a 100-step volume control via 3 segments of resistorsand switching relays, offering precise control over a volume range, meeting the needs of even the most sensitive IEM users.

The RU7 supports PCM up to 384 kHz and native DSD from DSD64 to DSD256. All digital audio signal will be converted to the designated DSD format before feeding to the 1-bit discrete DAC circuit.

To minimize interference, the internal circuitry is divided into TWO 6-layer PCBs, with digital and analog circuitry installed on separate boards. This protects the integrity of the signal, ensuring that noise from the reference clock and DSP does not enter the amplification circuit.

The discrete resistor network is a low-power DAC circuit compared to other highly integrated DAC chipset, it minimizes the power consumption of the mobile source. Redesigned amplification circuitry dramatically increases output power while keeping overall power consumption at 110-110 mA.

Low power consumption allows RU7 to be compatible with the following digital audio sources:

• Android-based mobile devices.
• iOS and iPAD OS mobile devices.
• MacOS computers.
• Computers with Windows 7/8/8.1/10.
• Digital audio players with USB audio output.

The 128x64 pixel OLED screen displays playback information with good visibility. The RU7 is smaller and lighter, beveled for better handling. All surfaces are gently curved to enhance the look and feel.

It brings with it a handmade magnetic leather case tailored to the device, achieving an elegant presentation. Two circular metal plates with adhesive tape pad are also included.

• RU7
• Type-C Cable
• USB A-C adapter
• User Manual
• RU7 case

• DAC: Discrete 1-Bit DSD DAC
• USB: Type C
• Digital decoding: PCM 44.1kHz - 384kHz. DSD64/128/256 native
• All to DSD: native DSD64/128/256
• Chassis: CNC
• Headphone output: 3.5mm - Single-Ended
• Line output: 4.4mm Balanced
• Input: 0.96" 128 x 64 OLED
• Dimensions: 66mm x 24mm x 12mm
• Weight: 25g

• Output power: 160mW @32 Ohms
• Frequency response: 20Hz - 42kHz
• THD+N: 0.006%
• Dynamic range: 115dB
• SNR: 114dB
• Channel separation: 76dB
• Output impedance: 0.5 Ohms

• Output power: 400mW @32 Ohms
• Frequency response: 20Hz - 42kHz
• THD+N: 0.006%
• Dynamic range: 115dB
• SNR: 112dB
• Channel separation: 92dB
• Output impedance: 1.0 Ohms

• Output power: 1.2Vrms @32 Ohms
• THD+N: 0.02%
• Dynamic range: 114dB
• SNR: 113dB
• Channel separation: 100dB
• Output impedance: 0.5 Ohms

• Output power: 2.4Vrms @32 Ohms
• THD+N: 0.02%
• Dynamic range: 114dB
• SNR: 113dB
• Channel separation: 102dB
• Output impedance: 1.0 Ohms