Cayin RU7: Portable USB DAC/Amp Dongle

Connected to the USB interface of cell phones, tablets and computers, the Cayin RU7 converts the songs stored on them or streamed from a music service with the precision of a discrete 1-bit resistor network DAC developed by Cayin.

The RU7 meets the high expectations of demanding hi-fi enthusiasts for mobile music playback and compensates for the limited audio capabilities of smartphones, computers or tablets. The DAC is simply connected to the USB-C socket. Once connected between the playback device and headphones, the RU7 now converts the digital audio stream into an audible analog signal.

The signals are converted by a discrete 1-bit resistor network in a ladder structure with 128 thin-film resistors, arranged in four groups of 32 resistors each, which already demonstrated its outstanding performance in the current DAP Cayin N7. The DAC also processes PCM signals up to 384 kilohertz and DSD streams up to DSD256.

The all-to-DSD mode has also been adopted from the Cayin N7. This allows high-quality streams in DSD format to be processed natively on the smartphone or signals to be converted into the format before they are passed through the converter network. Signals can also be decoded as PCM streams up to a sampling rate of 384 kilohertz.

The RU7 has a 3.5 millimeter jack socket and a balanced 4.4 millimeter Pentaconn connection. The sound quality of the balanced four-channel technology can get even more out of high-resolution material with the right headphones. The jack connection delivers 160 mW and the balanced output even 400 mW. The resistance on both connections is 32 ohms. Even power-hungry headphones should therefore be able to get going with the RU7 with full enjoyment.

The simple and elegant design of the mobile converter in dongle format is also impressive. The rounded edges and black finish create a stylish look. The OLED display with a resolution of 128×64 pixels provides precise information about the data rate and playback volume.

The accessories include a leather case. There are also magnets with which the DAC can be securely attached to the smartphone case without leaving any residue. The RU7 can be easily connected to Android smartphones or iPads using the USB-C cable supplied. A USB-A adapter completes the set.