Other than that, RU6 thankfully is so very spartan as it does not have any EQ functions. And I am perfectly fine with this as I have never used any EQ for any of my gears since forever. For those wanting to alter or color the sound with EQ, then the W2 would be a better choice. The Cayin RU6 was the company’s debut dongle as well as the first-ever dongle to be launched using R-2R technology. It was also our Top Gear 2021 Award winner. You can read our full review of the RU6 here from the same year. Technical Now this was with both using their respective SE outputs and dropping the power down. There is enough power for both IEMs to be adequately driven but once you switch to the RU7’s stronger balanced output the amount of channel separation and dynamics was noticeably improved. Questyle M15

The frustration points doubled up because I actually liked the sound overall. I came away more disappointed than anything; like a good idea or two got lost along the way somewhere and were left behind. The Analogue Discrete R2R tonality is something I have grown very fond of. The Cayin Ru6 delivers the R2R performance within a very portable size and the tonality is comparable to any R2R DAP. It has the warmth of any R2R typical tuning and can no way be considered bright. To be honest, it is quite difficult to tell the two settings apart and it requires attentive listening and good headphones. Despite being Analogue, RU6 exhibited exceeding competency with technicalities. Tested with my listening gears, what I am hearing is super transparent resolution throughout the dynamic range. Being Analogue sounding does not mean it has to be fuzzy. Details articulation is crisp and convincing, so is the resolution of imaging. The more resolving the pairing partner the better it is. In fact when paired with my ER4SR and Shure KSE1500 I am hearing every micro details that are available in the recordings. The Ronin has a warmer character but also a flatter bass response. The RU7’s beefier sub-bass tuning gave this pairing a bit more heft and a solid bass fundamental compared to the RU6.The biggest difference between the Go and Gold bars is that the Gold bar sounded less congested during complicated passages and everything keeps its place and shape.The Go bar seems like it is working too hard and gets things start to fight each other. Not to mention that the Go bar is a bit more “boomy” in the low end and less overall controlled and refined. The top end also was slightly hazier and did not have quite the clarity of the Gold Bar. OTG decoding from both is on par for lossless with the M15 offering up to DSD256 native and PCM 32BIT/384kHz but with an additional 8X MQA hardware unfolding capability which the RU7 does not have. Instead, the RU7 will give you an “All-to-DSD” upsampling option which brings its own unique flavor to the table. 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. It’s almost impossible to follow up on all of them, but in all honesty, I don’t think that’s needed either. There are some really good and affordable USB dongles out there from the bigger brands and looking at those probably gives you a 90% on the market and possibilities. Think AudioQuest, Fiio, Cayin, EarMen, xDuoo, etc. Dongle wars, it’s (not?) for everyone. Bass is always full and reaches down really low when needed. The layering is good but it isn’t the fastest and tightest kind of bass. Especially the subbass regions suffers from this, and as such it can sound a bit loose at the very low end. Bass is always punchy and present and warmer in presentation. It’s not a bass heavy sound, but it certainly isn’t bass shy either and for the real “neutral sound type” fans out there, its presence already might be a bit much. By contrast, the Cayin RU6 is significantly more powerful than the headphone output on my desktop PC’s motherboard (Gigabyte Z390 Aorus Master). With the gain set to low, the difference becomes smaller. Fortunately, the perceived sound quality is the same with low and high gain, so you can really just have it on high all the time. (Photo: Cayin) The sound of the Cayin RU6

I used the Cayin USBC to Lightning Cable that came with my personal RU6 except for the GOld Bar, which I had to use its included USBC to Lightning Cable since the Cayin cable won't work with it.The RU6 is a scaled-down implementation of the R-2R resistor ladder network DAC from R01 Audio Motherboards. I don't have a lot of information at this stage but I'll update the thread and the first post regularly until we have the complete product announcement clarify all the details to our users. This is what I can share at this moment: The treble section is clear, energetic and extends just far enough. It isn’t the most treble energetic DAC/AMP but it perfectly matches with the mid and bass smoothness. Treble will not offend anyone and it always is mature and polite. The sound had a cookie cutter feel to it. Part A meets Spec B, without any real promise of nuance. The very top may be a bit too sharp if your headphones run bright. I noticed it with HD280, and that is very much a "not bright" headphone sub-8Khz.

The bass in Lorde’s “Royals” is deep, without sliding out. And Lorde’s voice is fine and rich down in the tonal range. And while she doesn’t show her most airy side at the top, it works upwards too. With oversampling enabled, the information at the top comes through more, but at the same time the sound becomes flatter with poorer bass. Then I can better live with a little restrained overtones. There’s nothing ‘digital’ about the sound – it does indeed sound analogue. But what’s so outstanding about it is you’re not giving up any fidelity for the natural tone. It doesn’t compromise on technicalities to give you that silky smooth presentation. The FC6 does have an edge in decoding capability with an excellent DSD512 and PCM 32BIT/768kHz capability as well as MQA 8X unfolding. The RU7 is capped at DSD256 and PCM 32BIT/384kHz and has no MQA unfolding capability albeit there is some debate on how useful that will be in the long term. Sound differences: Both have a similar sound signature: Warm-Neutralish that at least goes up a few levels above the UA5 to me, more highs info than the RU6 and more defined lows also than the RU6. The mids to me on both dongles aren't tasty to me like the RU6 (since I prefer how the OG R2R sound handles mids), but they won't lie to you and is very defined with vocals and not sounding too upfront. GOld Bar however is the better unit than the regular Go Bar, it is at least two levels up IMO than the Go Bar and I see why people really like to get their hands on the GOld Bar. I think the GOld Bar is for the serious music listener who want the best a dongle can perform without lying to you if the recording is good or bad. The RU6 on the other hand has the OG R2R sound that messes together, and I prefer that if I had to be honest. Oh yes, RU6 has more sound staging over the Bar units but not a lot more.

Timbre is utterly natural and so close to reality that in the end you forget about the technicalities as you are immensely drawn to the music, song after song as the time passes by without noticing. It was also the only one out of the four that responded to the volume control on the iPhone. For whatever that is worth. The other three, it did not matter. iFi Go Bar + GOld Bar: Both Dongles will be similar in IO and sound signature, but differences if you read below. Lets get the IO out of the way, it's fully button based with no OLED/LED screen. To see what is turn on/off, the bottom of the unit uses LED lights to tell you bitrate and options on/off. I'm not a fan of this at all, but since both units don't use a screen then in theory the units will last longer since on the other units you need the screen to see what options you are adjusting. So if the screen dies out, you are semi-screwed. On the side of the unit it has buttons plus iFiMatch switch. Another button is to turn on xSpace and xBass DSP stuff, which I didn't use at all. Hold both volume buttons and you can turn on/off Turbo Mode. Turbo Mode makes a good difference on sound quality and it made the DD drivers in my Kato preform better. With that being said, it might be best to not use Turbo Mode on really sensitive IEMs.

Decoding levels are similar at DSD256 and PCM 32BIT/384kHz and both have sampling options though the basis for each is quite different. For the RU6 you have the classic NOS/OS option whereas the RU7 will offer you an “All-To-DSD” allowing you to process all audio from DSD64 to DSD256. Both will alter the tonal presentation in appreciable ways. Switching to the OS mode doesn't induce extra digitus but the sound somewhat loses some of its analogue, organic magic. Also, for the RU6, both DSD and PCM go through the same multi-bit, (24BIT) conversion and upsampling process before being decoded. Whereas all digital audio goes from PCM to DSD, (all-to-DSD), inside the RU7. In contrast the KA3 is more extended, faster, with increased clarity and more detailed presentation but it sounds somewhat leaner while it can't touch the naturalness and physicality of the RU6.The Sparrow might be a hair more resolving but the RU6 has more character and an organic tone. One other thing I notice is the RU6 has a wider soundstage and more tangible layering than the Sparrow. At the end of the day, the differences are minute and choosing between the two will come down to sonic character, size and features. Verdict On the other side of the spectrum, RU6 is as amazingly competent driving super sensitive stuffs like multi drivers hybrid IEMs. My TRN VX Pro, having 9 drivers per side and with super sensitivity, does not exhibit any unsavory floor noises nor does it sounded edgy or shouty. In a market already flooded with delta-sigma USB dongles that sound more or less the same, the RU6 with its natural timbre and organic character is a welcomed addition.