Hi Fi/Home Theatre & Portable Audio

Cayin RU6 R-2R Dongle DAC/Headphone Amp Unveiled

Cayin have unveiled a rather unique Dongle DAC that looks to be quite different than the rest of the products currently available. The Cayin RU6 R-2R Dongle DAC/Headphone Amplifier features something we have not seen before in the category; an in-house developed 24-bit discrete R-2R resistor

ladder circuit that can decode up to 384kHz.

Cayin has gone from being an unknown company in 1994 to a significant player in the headphone space. The brand launched with a series of stereo tube amplifiers that very quickly differentiated themselves from the other budget options of the day.

Cayin RU-6 Discrete R-2R DAC with Headphone Amplifier

The quality of their affordable tube amplifiers caught the attention of the headphone community and the requests for an affordable headphone amplifier started pouring in; the brand responded with the HA-1 and HA-6 headphone amplifiers and the floodgates opened.

Fast forward to 2021 and the brand now offers 5 desktop headphone amplifiers, 2 portable headphone amplifiers, 5 DAPs, and 2 earphones. The success of their headphone-related products enabled the brand to expand their offerings to include 3 CD players, 2 DACs, and 10 stereo amplifiers.

The one product missing from their arsenal has been a Dongle DAC; one of the fastest growing segments in the headphone category and a market that Cayin could not afford to ignore any longer.

Cayin RU-6 Discrete R-2R DAC Parts

Cayin doesn’t have a history of offering the same products as everyone else and the Cayin RU6 is not your typical Dongle DAC. A majority of manufacturers are using SOC designs (system on a chip) that allow them to build a finished product using the least effort and fewest number of components; the Cayin RU6 tosses that methodology out with the ear wax container.

Cayin had previously introduced an R-2R amplifier module for their N6ii DAP so some of the technology here is trickle down. The 24-bit resistor ladder is similar to what was used in the N6ii module, but a more cost effective resistor is used to keep the price in line with expectations and make the product affordable.  

Cayin RU-6 Discrete R-2R DAC Side

Cayin discovered that using the source to control volume digitally introduced way too much noise, so they decided to use a physical volume control on the RU6. They also discovered that there was not an available volume control that fit their needs; none matched their desired specifications or operational standards.

The only logical thing was to design and build their own 99-step thin film resistor array to handle the volume control on the RU6. 

Cayin RU-6 Discrete R-2R DAC with plugs

From there they added optional oversampling, two gain modes, both balanced (4.4mm) and singled-ended (3.5mm) outputs, compatibility with iOS, iPadOS, Android, Windows, most DAPs (via USB-C), and a 1-inch OLED display so all settings are visible without guesswork or multiple button presses to get to the mode desired.

The 3.5mm single-ended socket (0.5 Ohm impedance) delivers 138mW into 32 Ohms; and the balanced 4.4mm Pentaconn socket delivers 213mW into 32 Ohms.

Cayin RU-6 Discrete R-2R DAC connected to smartphone

The casework is an aluminum stick that measures 65 x 25 x 14mm; the equivalent of two packages of gum and weighs 28 grams.


Cayin RU-6 Discrete R-2R DAC PCB

Cayin RU-6 Discrete R-2R DAC Exploded


Cayin RU-6 Specifications

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