Included were a short, properly shielded usb-c to usb-c OTG interconnect cable and a cool usb-c to usb-A adapter to use RU6 with devices that have standard usb port. The CP32E are fairly sensitive as far as driveability goes, but still have black background with good sources to my ears.

The chassis is a single block of sand-blasted aluminium with matching metal buttons and a glass faceplate through which the OLED display is visible. By the time Cayin completed the R01 Audio Motherboard for the N6ii DAP, they noticed that the R-2R resistor ladder network could be implemented as a low power consumption DAC circuit that offers outstanding audio performance. The same can be said for the rest of my gears and even the normally "narrow-ish" Fostex T40RP MK3 sounded sensibly spacious.

To minimize interference, the RU6 circuitry is split into two 6-layer PCBs, with digital and analog circuit installed on separate boards. The OLED screen will display sampling rate, volume level, gain H/L and whether you are using NOS or OS mode. When off-the-shelf volume options cannot meet the high precision, low noise, low power consumption requirements of RU6, Cayin developed their own discrete resistor array volume control. As a result, OS mode offers better measurable performance, however, it can be argued that the purer signal provided by NOS mode introduces fewer artefacts, phase distortion and jitter.

The RU6 can pick up a bit of EMI from a phone and cause some faint hiss in the background which is audible on more sensitive IEMs. In terms of dimensions, the RU6 is slightly larger than your typical dongle but hardly to an extent that pocket or portable use become awkward.

It subverts what you may expect, delivering powerful bass but also an energetic and detailed top end. Natural is the word to use again, not only to define the timbre but also for expressing the decay, the notes are born and then fade away with the perfect timing. In this post, we review the Cayin RU6 which is the first-ever 24BIT discreet R-2R implemented dongle-type portable DAC and headphone amplifier.

To me, the biggest appeal of RU6, it was designed with a legacy Rail to Rail Array Resistors audio processing which clearly revealed the intent by Cayin on why they choose it - True Analogue sound.This is the first time that this has been implemented on portable dongle-type decoders such as the RU6. Adding Cayin C9 amp beefs up the bass a bit with more weight in sub-bass and mid-bass, but even without C9, it was still a great pair up. I haven't had that same level of uppermids harshness since then, and initial warm-up period was only a minute or two as this unit is quite small and getting it up to operating temperature should be quick. steps volume control through 9 segments of resistors and switching relays, meet all the RU6 requirements and transparent to maintain the natural sound signature of R-2R DAC. This safegaurds the signal integrity, making sure that the noise from the reference clock and DSP will not affect the amplifier circuit.

It comes packed with single Cirrus Logic CS43131 DAC chip and good build and some nifty features including BT and the volume dial. For example with my TRN VX Pro which is already natively wide sounding, I am hearing effortless headroom of soundstage that can make me forget I am listening to an IEM. As for the advantage of R-2R, unlike delta-sigma dac chipsets, it does not require a digital noise filter nor a feedback loop design, so it is born to be very quiet in the background and at the same time very unaltered in tone. But at the same time, you get a bird’s-eye view of all the settings at once on its 4-line display without a need to go to the next page.Under the oversampling mode, the digital stream is up-sampled to 384kHz, boosting resolution, reducing noise, and enhancing the anti-aliasing of the digital signal.