ЦАПы — Cayin RU3

The RU3 is a pocket USB DAC and headphone amplifier from Cayin, the Chinese maker of valve and solid-state electronics, built into a CNC-machined aluminium shell measuring 60 x 25.4 x 11 mm and weighing 24 g. It connects over USB-C to a phone, tablet or laptop on one side and headphones on the other, and it was listed at USD 99 with a USB-C cable in the box, in black, purple or light cyan.

Key specs that matter

Conversion runs on one ESS ES9069Q chip used in a dual-channel arrangement based on the ESS HyperStream IV Dual DAC architecture with SABRE HiFi technology. The chip accepts PCM up to 32-bit and 768 kHz and plays DSD512 natively. Two jacks are fitted - a 3.5 mm single-ended socket rated at 180 mW per channel and a 4.4 mm balanced socket rated at 560 mW per channel, both into 32 ohm. Cayin quotes a signal-to-noise ratio of 115 dB single-ended and 117 dB balanced, THD+N of 0.0018% and 0.0015% respectively, and a frequency response of 20 Hz to 50 kHz within 0.2 dB.

Engineering and use context

USB traffic is handled by an SPV5068 bridge, a dual-core RISC-V audio processor, which lets the RU3 run in UAC 1.0 or UAC 2.0 mode. That covers Android, iOS, Windows and macOS, and the unit also works without drivers on a PS5 and a Nintendo Switch. The output stage pairs two TI OPA1602 op-amps with two SGM8262 low-noise headphone driver chips in a fully balanced quad-drive layout. A HYP mode gives the higher output ceiling, while STD mode trims current draw to spare a phone battery. Both sockets double as line outputs at a fixed level when switched from phone mode. A 0.96-inch IPS colour display on the body shows the incoming format, gain, EQ status, power mode, UAC mode and volume, and physical buttons on the side handle control without a phone app. The Cayin Control App adds a 100-step volume scale, a choice of five digital filters and a 10-band equaliser.

Pairing

The balanced socket and its higher current suit full-size headphones of moderate impedance, while sensitive in-ear monitors are better served by the single-ended jack in STD mode. In line mode the RU3 can feed a desktop headphone amplifier or powered speakers from a laptop, turning a phone into a small streaming source for a larger system.

Alternatives

Cayin's RU7 is another dongle DAC from the brand, using a discrete 1-bit resistor network of 128 thin-film resistors with PCM to 384 kHz, DSD up to DSD256 and 400 mW from its 4.4 mm output.