Cayin RU6: R-2R USB Dongle DAC with Head-Amp
Jan 9, 2022 at 9:46 PM Post #1,486 of 3,737
I seem to prefer the NOS setting on the RU6, however I wonder if Tidal Masters are oversampled when they are processed by Tidal?

Sorry to bring up MQA again.
You can see!
 

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Jan 10, 2022 at 4:42 AM Post #1,488 of 3,737
@ryanjsoo has published a comprenhensive review on RU6, I always enjoy reading Ryan's review, they are very informative but not strongly opinated, so we can always gathered useful detail even when we have a different perference on music presentation. His photos are very appealing toop, even with boring boxy items like RU6. :wink:

1641807797308.png
 
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Jan 10, 2022 at 7:54 AM Post #1,489 of 3,737
After almost one week and +50 hours of listening to the Cayin RU6 I’m ready to share my more detailed opinion.

Cutting to the chase, I’m now actively searching for a Cayin n6ii with R01 (or other R2R dap) and a good R2R dac for my home audio system. Guess that says something of my opinion of the Cayin RU6…

Disclaimer

As always my ears are my ears, and my impressions are my subjective impressions. I honestly find it hard to put words in ”how something sounds” and the music library and timbre preference also plays a major role in perception of a device. I’m not a true believer in “audiosciencereview”, resolution >130 dB and SNR >120 dB etc., as music ultimately is all about the feeling and enjoyment created by the music.​

General observations
  • Pairing with different IEMs is of course affecting the overall perception of upstream equipment
  • My assessment here has been done using the UM MEST MkII with 3.5 mm cable
  • My ESS dac/amp dongles are in general a bit more detailed and analytical than the RU6
  • My ESS dac/amp dongles are in general more prone to sibilance and fatigue after longer listening sessions
  • For my ESS dac/amp dongles the amp implementation is coloring the sound into warmer or colder timbre (i.e. more or less shrill sounding)
  • For normal listening the “brain burn-in” makes it hard to judge diminutive differences in timbre and sound quality
  • I see no real life need for MQA (apologies to any still existing audiophile fan of MQA)
  • I see no real life need for higher bit resolution than 24 bits (I’m more than 50 years old and my hearing is what it is in the upper trebles)
  • I prefer device volume controls over UAPP (or other player) volume controls
  • On an R2R dac NOS is the only filter mode I would consider as these devices are bought for their “analog sounding” characteristics
  • 4.4 mm balanced is always better than 3.5 mm single ended, but again for this assessment 3.5 mm single ended was used for a like for like comparison
  • On the RU6 and for this comparison I prefer the high gain setting when using the 3.5 single ended output as I perceive this to render in better dynamics (no need for the raw power on IEMs or <60 Ohm headphones)
  • The RU6 is a wonderful device with a warm and cosy timbre while maintaining sufficient detail perfect for longer non-fatiguing listening sessions in a home or office environment
  • I need to buy a good R2R dap as a complement to my phone and dongle setups (my eyes are currently on the Cayin n6ii Ti)
  • I need to buy a good R2R dac for my larger and very stationary home audio system (my eyes are currently on the Musician Pegasus)
Comparisons
iBasso DC05 - RU6 has a warmer timbre, not as analytical but without lacking anything in terms of details and perceived resolution. I find the DC05 to have a tad better and a tad more airy treble representation bordering to sibilance, and the RU6 has far better bass/mid bass representation with full weight and warmth. For mids and vocals I find the RU6 very natural whereas the DC05 is more forward. Overall I prefer the RU6 for longer sessions due to the warm, cosy feeling that it provides.​
I would recommend the RU6 for a larger spectrum of IEMs with different timbres, whereas I would not recommend the DC05 for bright IEMs unless you are a true treble-head. Furthermore the RU6 is less sensitive to imperfect recordings. For music on the go with “darker“ IEMs the DC05 is good and inexpensive option.​
THX Onyx - More similar in initial timbre. I find the RU6 a bit more warm and natural sounding, and a tad less analytical. On timbre the Onyx is a bit more mid/treble forward and shines over the RU6 when doing analytical listening sessions with e.g. electrical guitar plucking, good female vocalists and electric pop with good mixing. I find the Onyx to have a bit faster bass response and slightly better punch, but for longer listening sessions I get fatigued by the more emphasized mids/treble on the Onyx.​
I would recommend both the RU6 and Onyx for a larger spectrum of IEMs with different timbres, whereas I would not recommend the the RU6 for music on the go where the Onyx is a better choice given more power (single ended) and better portability. Furthermore the RU6 is less sensitive to imperfect recordings than the Onyx.​
Audioquest Cobalt - RU6 every day of the year. I don’t even like the Cobalt for some reason.​
NextDrive Spectra X - RU6 every day of the year. The Spectra X was good when it was released, but time flies and today i find it a bit harsh sounding.​
 

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Jan 10, 2022 at 9:40 AM Post #1,490 of 3,737
After almost one week and +50 hours of listening to the Cayin RU6 I’m ready to share my more detailed opinion.

Cutting to the chase, I’m now actively searching for a Cayin n6ii with R01 (or other R2R dap) and a good R2R dac for my home audio system. Guess that says something of my opinion of the Cayin RU6…

Disclaimer

As always my ears are my ears, and my impressions are my subjective impressions. I honestly find it hard to put words in ”how something sounds” and the music library and timbre preference also plays a major role in perception of a device. I’m not a true believer in “audiosciencereview”, resolution >130 dB and SNR >120 dB etc., as music ultimately is all about the feeling and enjoyment created by the music.​

General observations
  • Pairing with different IEMs is of course affecting the overall perception of upstream equipment
  • My assessment here has been done using the UM MEST MkII with 3.5 mm cable
  • My ESS dac/amp dongles are in general a bit more detailed and analytical than the RU6
  • My ESS dac/amp dongles are in general more prone to sibilance and fatigue after longer listening sessions
  • For my ESS dac/amp dongles the amp implementation is coloring the sound into warmer or colder timbre (i.e. more or less shrill sounding)
  • For normal listening the “brain burn-in” makes it hard to judge diminutive differences in timbre and sound quality
  • I see no real life need for MQA (apologies to any still existing audiophile fan of MQA)
  • I see no real life need for higher bit resolution than 24 bits (I’m more than 50 years old and my hearing is what it is in the upper trebles)
  • I prefer device volume controls over UAPP (or other player) volume controls
  • On an R2R dac NOS is the only filter mode I would consider as these devices are bought for their “analog sounding” characteristics
  • 4.4 mm balanced is always better than 3.5 mm single ended, but again for this assessment 3.5 mm single ended was used for a like for like comparison
  • On the RU6 and for this comparison I prefer the high gain setting when using the 3.5 single ended output as I perceive this to render in better dynamics (no need for the raw power on IEMs or <60 Ohm headphones)
  • The RU6 is a wonderful device with a warm and cosy timbre while maintaining sufficient detail perfect for longer non-fatiguing listening sessions in a home or office environment
  • I need to buy a good R2R dap as a complement to my phone and dongle setups (my eyes are currently on the Cayin n6ii Ti)
  • I need to buy a good R2R dac for my larger and very stationary home audio system (my eyes are currently on the Musician Pegasus)
Comparisons
iBasso DC05 - RU6 has a warmer timbre, not as analytical but without lacking anything in terms of details and perceived resolution. I find the DC05 to have a tad better and a tad more airy treble representation bordering to sibilance, and the RU6 has far better bass/mid bass representation with full weight and warmth. For mids and vocals I find the RU6 very natural whereas the DC05 is more forward. Overall I prefer the RU6 for longer sessions due to the warm, cosy feeling that it provides.​
I would recommend the RU6 for a larger spectrum of IEMs with different timbres, whereas I would not recommend the DC05 for bright IEMs unless you are a true treble-head. Furthermore the RU6 is less sensitive to imperfect recordings. For music on the go with “darker“ IEMs the DC05 is good and inexpensive option.​
THX Onyx - More similar in initial timbre. I find the RU6 a bit more warm and natural sounding, and a tad less analytical. On timbre the Onyx is a bit more mid/treble forward and shines over the RU6 when doing analytical listening sessions with e.g. electrical guitar plucking, good female vocalists and electric pop with good mixing. I find the Onyx to have a bit faster bass response and slightly better punch, but for longer listening sessions I get fatigued by the more emphasized mids/treble on the Onyx.​
I would recommend both the RU6 and Onyx for a larger spectrum of IEMs with different timbres, whereas I would not recommend the the RU6 for music on the go where the Onyx is a better choice given more power (single ended) and better portability. Furthermore the RU6 is less sensitive to imperfect recordings than the Onyx.​
Audioquest Cobalt - RU6 every day of the year. I don’t even like the Cobalt for some reason.​
NextDrive Spectra X - RU6 every day of the year. The Spectra X was good when it was released, but time flies and today i find it a bit harsh sounding.​
Thanks for the review!

Can you please comment on the hardware that is providing the RU6’s input signal and power?

Can you comment on why the balanced output is “always better than 3.5mm single ended”, especially because the RU6 balances the output via a separate amplifier on the output instead of 2 DACs up front?
 
Jan 10, 2022 at 10:21 AM Post #1,491 of 3,737
Thanks for the review!

Can you please comment on the hardware that is providing the RU6’s input signal and power?

Can you comment on why the balanced output is “always better than 3.5mm single ended”, especially because the RU6 balances the output via a separate amplifier on the output instead of 2 DACs up front?

RU6 is single-ended designe from DAC to 3.5mm headphone output, and that include the volume control which is 2 channel only. A fully balanced design requires 4 channel volume control. The 4.4mm phone out of RU6 is balanced driven, it does meet the differentiate amplification condition technically. Althought it won't have all the advantages such as channel seperation of fully balanced design, it does offer more headroom and current capability.

You cannot determine whether the circuit is single-ended or balanced based on number of DAC. One or two DAC is not a the determining factor, especially on R-2R DAC design. You have to look at the output stage of the DAC circuit design. Some DAC chipset can provide differentiate output without needing 2 DAC.
 
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Jan 10, 2022 at 10:24 AM Post #1,492 of 3,737
Well I bought this dongle to pair with my JVC but I’m using it with by ZMF VC when I’m away from my desk and result is very satisfying. Great for Vocals with ZMF
 
Jan 10, 2022 at 10:27 AM Post #1,493 of 3,737
@Andykong A midrange DAP with RU6's tech inside, 4 inch screen, good battery life and a bit more power will be a home run which will sell better than the N3 Pro.
We have three models in our DAP line up. The N3Pro is our "entry-level", N6ii is our midrange DAP, and N8 is our flagshp and soon to be replaced by N8ii. What you said is certainly feasible,
technically. :wink:

This would be all I need! Please consider looking into it :)

Also, thankyou @Andykong for being so active and involved with the community - it's this discussion and your work that will keep Cayin going from strength-to-strength.
 
Jan 10, 2022 at 10:57 AM Post #1,494 of 3,737
RU6 is single-ended designe from DAC to 3.5mm headphone output, and that include the volume control which is 2 channel only. A fully balanced design requires 4 channel volume control. The 4.4mm phone out of RU6 is balanced driven, it does meet the differentiate amplification condition technically. Althought it won't have all the advantages such as channel seperation of fully balanced design, it does offer more headroom and current capability.

You cannot determine whether the circuit is single-ended or balanced based on number of DAC. One or two DAC is not a the determining factor, especially on R-2R DAC design. You have to look at the output stage of the DAC circuit design. Some DAC chipset can provide differentiate output without needing 2 DAC.
Thanks Andy for your input regarding clarifying Cayin’s implementation of “balanced output”…

I think I just wanted to hear what @Frombauge would base his “always better” statement on, and what he heard from the RU6 that justified it.

At the risk of pushing the RU6 too hard; that is, to ask it to draw too much power from the iPhone’s lighting port, I’m presently weighing the cost of a 4.4mm balanced cable against the possible benefits to what I hear from 46ohm closed-back headphones. I find myself wishing I could borrow a nearly CA$300 cable, but finding one that would work with my headphones would be rare anywhere, impossible in Newfoundland. The RU6’s 3.5mm SE output is already much better than what I had been used to. It’s torturing me to want the best out of it…
 
Jan 10, 2022 at 11:05 AM Post #1,495 of 3,737
Thanks Andy for your input regarding clarifying Cayin’s implementation of “balanced output”…

I think I just wanted to hear what @Frombauge would base his “always better” statement on, and what he heard from the RU6 that justified it.

At the risk of pushing the RU6 too hard; that is, to ask it to draw too much power from the iPhone’s lighting port, I’m presently weighing the cost of a 4.4mm balanced cable against the possible benefits to what I hear from 46ohm closed-back headphones. I find myself wishing I could borrow a nearly CA$300 cable, but finding one that would work with my headphones would be rare anywhere, impossible in Newfoundland. The RU6’s 3.5mm SE output is already much better than what I had been used to. It’s torturing me to want the best out of it…
I found that the RU6 drives the following on the 4.4mm socket with plenty of headroom and great sound quality…
  • Sennheiser HD820 (300 ohms) high gain
  • Audeze LCD-XC (2019) high gain
  • Fostex T50RP high gain
  • Oppo PM-3 high gain on 3.5mm socket
  • Focal Elegia low gain
Source is my iPad Pro 12.9” series 3 USB-C
 
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Jan 10, 2022 at 11:24 AM Post #1,496 of 3,737
I have been using the RU6 for one week now and it is by far the less "digital" sounding DAC I have ever heard.
Timbre is decidedly different from any chip based DAC and I believe it is more natural on the RU6. Dynamics and details are very good and imaging is excellent.
The only thing leaving to be desired is soundstage, though it might be more realistic than the expansive soundstage of my Audirect Atom 2.

I just have one question.
Since the OS mode upsamples everything to 384khz, when I stream Qobuz and Tidal in DSD 256 (11.2Mhz) from Audirvana, there is no difference between OS or NOS mode on the RU6. Is that right?
 
Jan 10, 2022 at 11:39 AM Post #1,497 of 3,737
Thanks Andy for your input regarding clarifying Cayin’s implementation of “balanced output”…

I think I just wanted to hear what @Frombauge would base his “always better” statement on, and what he heard from the RU6 that justified it.

At the risk of pushing the RU6 too hard; that is, to ask it to draw too much power from the iPhone’s lighting port, I’m presently weighing the cost of a 4.4mm balanced cable against the possible benefits to what I hear from 46ohm closed-back headphones. I find myself wishing I could borrow a nearly CA$300 cable, but finding one that would work with my headphones would be rare anywhere, impossible in Newfoundland. The RU6’s 3.5mm SE output is already much better than what I had been used to. It’s torturing me to want the best out of it…

Shure 1540? 4.4mm will almost always work better for full size headphone pairing with RU6, the extra headroom are important to large dynamic drivers.

Having said that, I am not sure if it worth to spend CA$300 on headphone cable when you want to squeeze the final 5% or 10% from the $250 Dongle. This is a matter of personal judgement and priority.
 
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Jan 10, 2022 at 11:44 AM Post #1,498 of 3,737
I found that the RU6 drives the following on the 4.4mm socket with plenty of headroom and great sound quality…
  • Sennheiser HD820 (300 ohms) high gain
  • Audeze LCD-XC (2019) high gain
  • Oppo PM-3 high gain on 3.5mm socket
  • Focal Elegia low gain
Source is my iPad Pro 12.9” series 3 USB-C

I will add to your list:
Hd800s (300 Ohm) at 75-85 Low gain, 4.4
Ibasso SR1 (40 Ohm) at 50-60 L 4.4
Caliber 1H at 40-50 L 3.5
 
Jan 10, 2022 at 11:46 AM Post #1,499 of 3,737
I found that the RU6 drives the following on the 4.4mm socket with plenty of headroom and great sound quality…
  • Sennheiser HD820 (300 ohms) high gain
  • Audeze LCD-XC (2019) high gain
  • Oppo PM-3 high gain on 3.5mm socket
  • Focal Elegia low gain
Source is my iPad Pro 12.9” series 3 USB-C
That’s good to hear… but I have to wonder if Apple puts the same power limitations on the iPad’s USB-C as it does on an iPhone’s lightning connector. Whether or not this is a real problem with driving the RU6 with a iPhone remains conjecture as I consider it a rumor regarding reported dropouts in this forum thread, and because I cannot find any confirmation elsewhere on the web.

I figure I’d be able to judge the quality of “balanced” output by purchasing a ‘4.4mm to L&R RCA’ adapter cable, and hook the RU6 up to an auxiliary input on my Denon AVR, and then to A-B the RU6 outputs with my headphones of choice. But it still would be difficult to A-B critically, and wouldn’t make me any more comfortable with the possible power dependency problem with using with an iPhone.

You wouldn’t have an extra balanced 4.4mm cable for Shure SRH1540 headphones, would you?

Edit: I left some info out of my “A-B test”. I’ve already tried the RU6 with my Windows 10 JRiver computer. It works well, and it’s this I considered as a source for my test. However, I don’t see why I cannot use the iPhone instead and still connect the 4.4mm-to-RCA to my Denon. And, that may even also test the iPhone current draw question(?)
 
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Jan 10, 2022 at 11:52 AM Post #1,500 of 3,737
Source: Lotoo Paw 6000

Verite Closed @ 70 - 80, H, 4.4
HEKSE @ 60 - 75, H, 4.4

With the VC, however, I always had the feeling that something was missing.
With the HEKSE the playback is just beautiful, at no time do I feel that anything is missing.
:)
 
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