Cayin - RU6

Gives music a whole new dimension. Very detailed and clear. Love it!!

I’ve been following the Cayin RU6 since its launch in 2021. Back then, the price was closer to its original MSRP of $249. Recently, I noticed the price had dropped to $150, and to my luck, an unboxed unit was available for $135. I immediately placed the order. The HZ team informed me that the used unit had already sold out, but to my surprise, they kindly sent me a brand-new RU6 instead—exceptional service, as always!

To describe the RU6, in a world dominated by Canon RFs and Nikon Zs, this DAC feels like a Pentax K1000. If you’re a photographer, you’ll understand this analogy—it’s about classic, tactile analog quality in an age of razor-sharp clinical presentation. To my knowledge, the RU6 is the only R2R DAC in the sub-$150 category, and I’ve been eyeing it specifically to experience my Ilaiyaraja library as intended.

My reference DAC is the Topping DX1, which I use to play my entire library to DSD256 via HQPlayer. Since the RU6 supports only PCM, I configured it for PCM384 at 16-bit depth in NOS (no oversampling) mode. Based on measurements from L7Audiolab and Archimago, while the RU6 has 24-bit capability, its resolution is optimal at 16 bits, similar to CD quality.

The comparison between the DX1 and RU6 is fascinating. The DX1, powered by an AKM DAC chip, already delivers a smooth, flat presentation with fast decay. However, the RU6 stands out immediately with its spatial presentation, organic decay, and texture. The depth, layering, and improved timbre of instruments and vocals are distinctly noticeable. These subjective details were missing with the DX1, imo.

In terms of power output, my reference listening level with the DX1 requires the volume knob at 3 o’clock in low-gain mode (due to my PEQ settings and ReplayGain). On the RU6, the same volume required setting it to 90% in low-gain mode via the 3.5mm output. I didn’t test the 4.4mm port, as the RU6 is inherently single-ended, and the 4.4mm port merely uses an op-amp to deliver more power.

The only downside I noticed was the RU6’s ASIO driver. Unfortunately, I couldn’t get ASIO mode to work with HQPlayer and had to rely on WASAPI. Additionally, Cayin’s normal USB drivers aren’t compatible with the RU6/RU7 series, and no new drivers have been released since 2023 specific to RU6.

Overall, the Cayin RU6 is a breath of fresh air in the world of portable DACs, especially at this price point. If you’re looking for a warm, textured, and organic sound with exceptional spatial presentation, the RU6 is a must-try.

I am using RU6 in Car audio as a upgrade to Fiio BTR5. Good details and warm sound signature. Its a great experience with my ICE (Clarion HXD2 -- McIntosh amps - SB Acoustics drivers).

Firstly thank you so much HEADPHONEZONE..i received CAYIN RU6 portable DAC just in two days..My first impression is compact size with plug & play. sounding is natural, wider sound stage, clear, deep bass and nice vocal control. I tried all type of songs just amazing.I was searching perfect music device like this since ten years, finally I got it.guys don’t think too much if you want to best of best music experience in budget this is one. Once again thank you HPZ. I am big big fan of HPZ….🙏🙏

Having owned an EarStudio, Qudelix 5k, Eagle, Hip Dac 2, I was pretty reluctant to get another DAC as a daily driver. Having seen various rave reviews and the beauty of the R-2R capabilities in such a small form factory I had to get it.

First impressions were really good, esp the fact that I don’t have to EQ this DAC at all. It just somehow produces a sound that you don’t want to alter anymore. It can just drive anything. Tried it on my Blon B3, Aria, KZ10 and Sundara. It plays to the strength of all. Loved it on balanced out in my Aria esp.

That’s it. Just get it 😅👆🏻

Cayin - RU6 is my first-ever DAC amp. I haven't heard any others, so I can't compare or comment on the sound quality, but it sounds good and I'm pleased with the purchase.

I purchased 2 dac from headphonezone both are awesome. If you want sweet sounding dac like caramel then go for RU6 it feels like if anyone listened sennheiser they surely know what I am talking about. The depth and intensity of some tracks are incredible good same goes to RU6 dac provides you the almost same feel in your iems. One of the best portable dac ever to me .if you guy’s looking for power hungry headphones dac then go for questyle m15 this dac . M15 dac can easily handle most of the iems and headphones 2 like a piece of cake🤭 both are perfect. And headphonezone customer support heads off to you guys ❤️❤️❤️ but I have to mention one thing this dac RU6 have some issues with iPhone sometimes but work with android absolutely fine🙏

My passion for audio was uncovered during my school days. Back then we owned a Technics stereo receiver with vintage 3 way speakers which was a massive wow factor for anyone who listened to the audio output from it.
My primary preference of listening to music has been a Hifi system, and it still is, which has seen multiple brands (Paradigm, Focal, Quad, Klipsch, Polk, Mission, Sony, Bose, Altec) and types, including studio monitors, over the years. My previous system was Musical fidelity m5si/ M5CD combo with Monitor audio gold GS60 speakers. It was a killer combo which impressed anyone, including me, who listened to it. It was also the most expensive combo I had ever owned. As I shifted homes, I downsized to a smaller system with bookshelf speakers from various brands.
I do enjoy listening to music through portables and have owned a few headphones too.
Over the years, I have come across audio components which were breathtakingly impressive. Some of them are so good that you will think you are really there at the live music performance. Portables can sound incredible but can never quite sound like hi-fi in that regard. However my first mobile component which truly was revolutionary in its sound output was the ipod 1st gen with the then wired apple earbuds. It had a clarity I have never heard before from a mobile component. I took it to the office and had my colleagues listen to music through that to get their view as well. Everyone was astonished with the sound.
My first USB dac was an HRT music streamer ii. It made a difference to the sound, when I connected my desktop speakers through that. I compared its output to the PC's onboard audio. I even compared it to the onboard DAC from my Musical fidelity m5si/ M5CD combo (they both had USB DACs in them). They all had a difference in sound but each had its pros and cons.

Now I got the Cayin RU6 DAC which is an interesting R2R one as it sure doesn't sound like a typical delta sigma DAC. The build quality is easily the best I have seen on a USB DAC. The key differentiator or the USP of this DAC is the vocals take a sweet tone to it which is quite nice on certain types of music. When you do an A/B comparison, the overall sound gives a certain sense of thickness to it while the other standard DACs may sound a bit lighter. I would not call the Cayin sound to be a proper analogue one but it's fairly there in a small portable form factor.. It has enough power to drive headphones under 80 ohms to loud listening levels. The overall system synergy determines if this is the mobile DAC for you. I liked it quite a bit over the other delta sigma DACs like Shanling UA2 &Astell&Kern - PEE51(yes, unfair comparison by price). Those DACs have a bit more air to the presentation and some may like that. However Cayin RU6 is not a wow product like how I felt about the ipod 1st gen back then. Perhaps it's not meant to be. But I liked it over the other dongle dacs I had tried. It sounded quite good on my hifi as well.
However, my use for a mobile DAC seems to be reducing over time as I have the need to switch to office calls on the phone and for that my Samsung earbuds does the job with incredible convenience. There is no comparison to the sound quality between the wireless buds and full sized headphones like Audio technica ATH M50 or the Beyerdynamic DT770 pro. The latter type is any day preferable for me when it comes to listening to music. For the sake of above said convenience, I may consider selling this and get a wireless HP with mic from HPZ. But can't give up so quickly on this journey yet, can we :-)
If you have a HP which tends to sound enthusiastic, this DAC can make it more listenable for longer sessions. Do try the NOS mode with low gain for the smoothest sound output from this albeit less dynamic sound, The OS mode with high gain enabled makes the sound more dynamic and might suit your overall system.
One interesting observation on streaming audio is that Amazon prime music outputs all tracks at 192Khz. Apple or spotify music doesn't. Wonder what's the deal with that. I would not have known this if it wasn't for the display in Cayin DAC. This was on a Samsung phone.
Eddict Player gives original bit rate output from android mobile to the DAC. I know most use USB audio player Pro. The pic I have uploaded for this review shows the DSD file playing on my mobile on Eddict player. Notice the bit rate shown in the DAC. Feel free to write to [****] if you have any questions.
Also, HPZ is one of a kind in India and I am glad someone thought of it to bring such an excellent collection of audio products at a good price to us. Their customer support is good as well.

Just give this thing burn in around say 150 to 200 hours and see the magic..it becomes most resolving even in the NOS mode, highly technical, fantastic soundstage, deeper sub-bass extension/ rumble, treble roll off at the right point, fantastic details..I have no words as to how much I'm fond of these..just need to add a dedicated amp say topping nx7 to bring out the true potential of these as the only gripe I find with these are a bit struggling to drive high impedance stuff say earbud (Faaeal Rosemary - 150 ohm) compared to other my other fantastic dongle - tempotec e44, which looks less powerful on paper compared to ru6. It paired best with every IEM I have, especially with the S12 and Kotori audio Dauntless..All in all, ru6 is definitely a 5 star dongle in my books.

This is definitely a different class of a DAC amp. Its got enough grunt to drive even my HFM Sundaras to a satisfactory level. The sound that comes out of it can be described as an old school analogue sound an it is smooth as butter, glued together and tonally fantastic. Playing old recordings through it gave me a nice sense of nostalgia of growing up with this kind of sound. A visceral, thick, smooth, well integrated and modestly detailed. The supplied cable though is not robust enough and audio through it sometimes stutters because of its movement. Surely Cayin should take care of it considering the cost. I am also getting a faint digital interference noise on the left channel in between songs. These are not insignificant flaws but the sound that comes out of it mitigates them. Yummy indeed.

I had no clue that investing in a DAC could really transform your listening experience. Before this purchase, I had my own playlist of songs that sounded great with my existing earphones and headphones. I used to listen to only them with occasional new inclusions. After this purchase, the quality of sound has improved so much that songs from different genre also sound great (lows, mids and highs). When I am moving, I just plug this DAC to my mobile phone and use it with my headphones.

Some of the negatives include
1. Significant battery discharge, almost 20% for 90 minutes of listening.
2. Device becomes warm a lot
3. Sometimes it gets clumsy to carry it along with your phone in your pocket.