Cayin RU6 USB DAC Headphone Amplifier

Product Information

This safeguards the audio signal integrity and ensures the noise from the reference clock and DSP do not bleed into the amplification circuit. This is very high-quality volume control design that was frequently used in high-end preamps and integrated amplifiers.

However if I am going to be nitpicking, I would say that I would have preferred RU6 to exhibit just a tiny bit more of smoothness. Neat and simple it has the advantage of the hardware buttons and the OLED screen but it doesn't offer the same kind of customization as the FiiO KA3 does through the supporting application. 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.To overcome distortion that comes with an amplified weak signal, the RU6 incoming bit-stream is fixed at full volume, with 9 sets of resistors and switching relays enabling a total of 99 steps of fine volume control within –6dB to 0dB on each resistor set. USB Audio Bridge: receive different audio format from USB, go through high precision signal enhancement, output I2S bit-stream for subsequent processing. I’m sure most are aware of the R-2R DAC movement but for those that aren’t, these DACs differ entirely to those widely adopted on the market such as AKM and ESS, commonly dubbed Sigma-Delta DACs. That means a total of 96 pieces of precisely matched resistors are used to facilitate the actual conversion for the 24BIT stereo design. The RU6 has physical volume buttons for conventient control that also double as menu selection when entering mode settings.

Lawrence’, the midrange notes on the piano are forward and well tempo-ed and the RU6 renders the accordion and the Chinese string instruments nicely with good authority. There are no pops when powering the dongle on or off which adds to the refinement of the overall user experience. The oversampling mode adds extra texture and smoothness, putting together a retro, analog tuning with enhanced transients and a stronger outline. The hardware volume control buttons are backed by a sophisticated resistor ladder volume circuit, and users can select between Non-Oversampling or Oversampling mode through a simple menu setting. I was trying to resist the temptation to try this, but curiosity got the better of me, and I had to see how this little engineering and packaging wonder sounded.Treble sounded realistic as it is naturally vibrant, Mids as rich as the listening device capable of emitting, Bass having visceral density which is real and engaging.

Dongles are getting more and more popular and there must be dozens of brands right now with a USB Dongle in their product line-up. Unaltered and effortlessly articulated, the RU6 renders up-front vocal imaging and intimate midrange instrumental presentations with satisfactory resolving power. Switching to the OS mode doesn't induce extra digitus but the sound somewhat loses some of its analogue, organic magic. It didn’t sound too bad, but I wasn’t able to drive these headphones to their full potential, and added C9 to the output. It is Cayin's first ever DAC/Amp in Dongle form factor and most importantly, it is the very first non Delta Sigma Dongle ever.I used the RU6 with a salvo of different transport devices: My Samsung Galaxy S21 phone, my iPad Mini 6th Gen (USB-C model), my iBasso DX240 Digital Audio Player, my Asus Chromebook, my Dell Precision laptop, and my Intel Canyon Hades NUC desktop PC. Digital Filter-less, no post-processing, optimized in time domain, low phase distortion and jitter, no ringing artifact. The appearance is quite modern and minimalist while finish and build quality are excellent with the only negative being that the glass surface is a fingerprint magnet but if you ask me, I wouldn't care a lot. All of the dongles come with great features and amongst them the W2 and the RU6 are the most powerful ones.