Ever since its debut, I’ve been a big fan of the AKM 4490 chip in almost every device I’ve heard it in.  The Bifrost 4490 was a great midlevel DAC, I love the m9XX and the Modi 2 Uber with 4490 is an incredible value.  So, when I saw the Cayin iDAC6, I was extremely intrigued.  First, it was the only implementation I had seen that used dual AKM 4490 chips.  Secondly, it had the option of going fully balanced, and also having the ability to choose between tube and solid state analog output stages.  
 
I bought my unit from another Head-Fier used, who got his unit in one of the very first batches that were sold to the public.  He kept the amp, but after A/Bing his unit preferred his Yggdrasil to the iDAC6.  Given that Yggy is a $2000+ DAC that is generally considered the best DAC in the world, that’s not much of a slight on the iDAC6.
 
Gear used:  Unless otherwise noted, most testing was done with my TorpedoIII amp and HD800 headphones, unless otherwise noted Sonarworks calibration was applied to the HD800.  Inputs used were a mix of optical, USB and USB via Schitt Wyrd USB decrappifier.  
 
Looks:
 
The iDAC6 is a pretty classic looking medium/large DAC.  It’s appointed in a matte, brushed aluminum type finish, with a chrome polished knob and three chrome function buttons.  The volume on knob had a very tasteful white LED ring around it to indicate that the device was powered on.  A very standard LCD screen indicates necessary info like sample rate, mode, level, input type, output type, etc.  The LCD is slightly angled upwards, which makes reading it a bit easier since you will normally be looking slightly down at it while adjusting it.  A very subtle white screen printed cursive Cayin logo sits unobtrusively in the top left corner.
 
All in all, I would call it a very classy looking DAC that doesn’t really make any statements one way or the other looks wise.  It looks very typical of silver finished equipment.  
 
While not being larger than most DACs of its class, it is quite heavy.  I have mixed feelings about this, in that it’s no worse in this regard than competitors, but I also just don’t feel like DACs need to be this big any more.  This is doubly problematic because it runs so hot.  TO me the traditional argument for DACs being this large and heavy was because they needed to be that big to properly dissipate heat.  But this DAC still runs very warm.  Not unbearable to the touch or anything, but warmer than any tube amp I’ve ever owned.  In comparison to some of the newer top quality DACs I’ve tried, the footprint is quite large.  And as noticed during the tour, shipping for this item can be insane because it weighs about 15 pounds.  That being said, the size and heft does give it a feeling of being substantial.  Overall I’d call the size and heft a mild negative.
 
Features:
 
The iDAC6 features a full range of the normal selection of inputs and outputs to be expected of top range DACs: Inputs are: Optical TOSLINK, Coaxial TOSLINK, AES, USB Type B. Outputs are: Balanced XLR dual 3 pin, unbalanced RCA.  Output is on the higher side (2.2V RMS unbalanced, 4.4 V RMS balanced).  Input is selected by pressing the small chrome “source” button.  Output does not need to be selected, as they both are always active.  If you have amps plugged into both the balanced and unbalanced outputs, they will both receive signal from the DAC.  As far as I know there is no way to switch between them, other than simply unplugging from the output you aren’t using (or turning off the amp receiving that signal, obviously).
 
On USB DSD 64 and DSD 128 are supported natively, while up to 32/384 are supported through PCM.
 
Five filters that are native to the AKM 4490 chip are use selectable.  This was very interesting to me, because although I’ve had several DACs that use this chip, this is the first time I’ve had one that just used AKM’s filters unchanged.  The Grace m9XX only uses 4 filters, and as best as I can tell they’re slightly altered versions of the 4 AKM filters.  The Schitt products that use the AKM4490 do not allow the user to select the filter, and seem to use the Slow filter always.  The f filters are: Super Slow Roll Off, Short Delay Slow Roll Off, Slow Roll Off, Short Delay Sharp Roll Off, and Sharp Roll Off.  Here is a picture that AKM has released describing them:
 

 
This picture somewhat exaggerates the differences between the filters, which can be quite subtle.  Unlike the filters on the Grace m9XX, they are a bit more noticeable here.  I found slow roll off to be the best sounding, and unless otherwise noted, the rest of this review will be written about the sound with this filter employed.  Much of choosing the right filter will be based upon the music you listen to and your downstream amplifier, as one of the primary functions of these filters are to deal with issues in aliasing distortion and intermodulation distortion that can arise with some music in some setups.  This isn’t really the place to go into a ton of detail about how the filters work, but I will just say that most sources seem to agree that slow roll off is the best setting if you aren’t having issues elsewhere in your chain with IM or aliasing distortion.  The different filters can be switched by pressing in the large rotary knob.
 
In addition to the five filters, the iDAC6 also allows you to choose between solid state and tube output stages ****IF YOU ARE USING THE UNBALANCED RCA OUTPUTS****.  Make sure you are clear on that.  If you are using the balanced outputs, you are limited to the tube output stage.  When plugged into the RCA unbalanced output, you can switch between tube and transistor output by hitting the “timbre” small chrome button.  If you do this when plugged into the balanced output the iDAC6 will always output from the tube stage.  Even if the LCD says “transistor” if you are plugged into the balanced output you are getting the tube output stage.  Because of this, the tube stage is always on whenever the iDAC6 is on.  Even if you are running it in transistor mode through the RCA output, the tube output stage is still running.
 
The iDAC6 also allows you to alternate between two operation modes: pre-amp and line out mode.  The differences are thus: line out mode allows for the playing of DSD natively and pre-amp mode allows you to adjust the unit’s output level digitally via the AKM4490’s built in 32 bit digital volume attenuator.  If you want native DSD, you must use the line out mode, as pre-amp forces everything to go to PCM, since it needs to be PCM in order to do the digital processing that the volume control uses. 
 
So, now that the thorough description of the look and features, on to the meat of the review. 
 
Sound: 
 
The first thing I notice about the sound of this DAC, is the “heft” of its output, especially in the bottom end.  Comparing it to other DACs I own, with a given amp, it has very clearly the most punch and impact of anything I’ve ever tried.  I believe this comes from the output stage, rather than the chip/conversion stage.  The Grace m9XX, when run as a DAC only into my TorpedoIII is nowhere near as punchy as the iDAC6 through the RCA output is into the same amp with the same headphones.  As both of these utilize the same AKM4490 chip (albeit with the iDAC6 sporting two of them), I don’t think this can be a tonal characteristic of the chip.  It is even punchier than the Bifrost 4490, which is known for being a punchy DAC.  It just has an effortless sense of power when powering through transients.  At times, in certain setups, with certain headphones, it can sound almost “hard.”  This is especially evident when comparing it to the Modi Multibit, which has a sort of softness of sound to its output.  If you are trying to get a bit more “oomph” in your chain, this may very well be the DAC for you.  But if you have a super punchy amp and headphone, it may border on being too much.  There were times with the TorpedoIII and HD800 (both very punchy the way I have them setup) that the setup was so dynamic, that it was like it almost overwhelmed my ear and I was unable to hear detail in transients.  It’s not that the detail wasn’t there, I don’t think, it was that the setup was just too much for my ear.  It could be a bit fatiguing in this setup.  This held for both the tube and transistor output, although I think the transistor output was a bit less so, especially on bass transients.  The iDAC6 in tube mode could really produce some absolutely thunderous kick drums, for example, when paired with a punchy amp and a very lively headphone.  
 
With an HD650 though, this characteristic really shook off the Sennheiser veil, almost more than I’ve ever heard an amp doing.  Normally we think of needing just the right amp for the HD650 to come alive, but pairing it with the iDAC6 allowed some amps that I normally wouldn’t think of as being a good match with the HD650 to really shine.  The HiFiMan Edition X also really benefitted from this, as it’s characteristic “soft” sound was woken up just a bit, and while it retained its tonal character, it was a bit more lively and less “soft” sounding.  With the THX00, bass was even more addictively fun.  Drums sounded like thunder.
 
The second thing I noticed about the sound of the iDAC6 is a sense of easy spaciousness.  I wouldn’t say it sounds airy in the way that some Delta Sigma DACs can sound like you’re in a large, cold auditorium.  It often sounded like you were in a large room, but during summer.  I never felt claustrophobic, but I didn’t get a sense of airy spaciousness either.  Again, this characteristic held for both output types, but was most evident with tube output.  Soundstage was both a touch wider and deeper than other AKM4490 based DACs I’ve tried (m9XX, Bifrost4490, Modi 2 Uber 4490).  It doesn’t compete with the Yggdrasil, GuMBy or even MiMBy in terms of spaciousness, but acquits itself very well in that regard int he world of top end Delta Sigma DACs.  I never found myself wanting for soundstage with this DAC, but I have heard larger.  Imaging accuracy was excellent.  Separation was excellent.  It reacted well to when I turned on GoodHertz CanOpener for my crossfeed needs.  I have heard DACs that screw up the HRTF functions that CanOpener applies, somehow.  
 
Micro-detail was very good, but not truly class leading.  To me, this is where even the best Delta-Sigma falls short of R2R DACs.  They, at some point, seem to have to make a tradeoff between harsh and brittle tone or smoothing over some micro-detail.  While the Yggy, GuMBy and even MiMBy could preserve detail without having to be harsh, it seems the iDAC6 had to make this choice and opted for smoothness.  If this choice has to be made, it is certainly my preference that it go in the direction Cayin/AKM chose, which was smoother.  I abhor many of the Sabre based DAC that attack your sensibilities with brittle faux micro-detail.  It’s like many Delta Sigma DACs, because they’re missing some of that micro-detail pretend its there by making the tone harsh.  It’s sort of like when a photographer missed focus by an inch or two, and artificially over-sharpened in photoshop to make up for it.  The AKM4490 based DACs instead just smooth it out and make it sound great.  This has been a characteristic of every AKM4490 based DAC I’ve ever heard.  If anything the iDAC6 has the best micro-detail of any AKM4490 based DAC.  But there are DACs that are a bit better in this regard.  An example of how this plays out, is that you can hear tiny differences in the character of the reverb on some tracks with the R2R DACs, that were just a bit smoothed over with the iDAC6.  Now, this difference in detail is subtle.  I couldn’t even pick it out on an HD650, HE400i or Grado SR225e.  But on my HD800 it was there.
 
On the question of tube output vs. transistor:
 
To me, the feature that will garner the most headlines and confusion about this DAC is the tube output stage vs transistor.  There aren’t a whole lot of tube output stage DACs out there, and I don’t know of any that also let you choose transistor output stage.  To me, the tube output stage almost always sounded slightly better.  It lacked a certain edginess in transients that transistor had.  While the transistor output measures as having less THD, one of the things I’ve learned over the years in audio is that total amount of THD is less important than how that distortion breaks down.  The transistor output seems to have most of its THD located randomly in “harsh” high order harmonics.  The tube output stage (which operates *after* the transistor stage and acts more as a tube buffer) adds just a touch of low order harmonic distortion, which has the effect of smoothing the harsh edginess, just a bit.  I slightly prefer the tube output most of the time.  Think of it like this DAC basically has something like an iFi micro iTube built in.  As this costs $329 on its own, it’s quite a coup to have it built in and switchable.  In systems with no tube stage anywhere in the signal path I always preferred tube output stage.  But even in systems that had tubes otherwise in the signal path (TorpedoIII, for example) I still generally preferred the tube stage output, though I was able to appreciate the transistor output on some recordings a bit more.
 
 
Comparing to other DACs I either own or significantly demoed:
 
Grace m9XX: iDAC6 does everything the m9XX does except crossfeed just a little bit better.  For anybody who is familiar with the way the m9XX sounds, think of the iDAC6 as like an m9XX on steroids.  A bit more spacious (I believe due to operating two AKM4490s in dual mono mode), a bit more dynamic, a bit smoother, and a bit more detailed.  They’re entirely different products, with different usages obviously, but I’ve had a lot of m9XX owner’s ask me to make the comparison.  A lot of m9XX owners who bought the m9XX as their first high quality amp/DAC might eye the iDAC6 as a potential upgrade path for a full sized desk top rig, allowing the m9XX to serve as a smaller, semi-portable secondary option.  
 
Schiit GuMBy: this is the most clear tossup.  The GuMBy is a bit more detailed.  They both have similar tonalities though, leaning just a touch warm and inviting.  However, iDAC6 is more dynamic.  Bass transients (think kick drums, bass slaps, etc) have an additional weightiness to them that GuMBy lacks.  The iDAC6 hits harder, the GuMBy is a bit more detailed and spacious.  Which you prefer will depend on personal preferences and also your system.  I could absolutely see somebody with, for example, a HiFiMan HE1000 or Sennheiser HD650 based system preferring the iDAC6, to really make it hit harder and faster.  I could see somebody with an Abyss or HD800 preferring the GuMBy, not needing the additional impact, but being able to reproduce the extra detail.  It will be down to not just headphone, but also amp.  At this level, it really does come down to system synergy as much as anything.
 
Schiit Yggy: Yggy is better.  It has the detail advantage that GuMBy had, but also has the additional power and impact that iDAC6 has.  Now, the Yggy isn’t as tonally versatile as the iDAC6 is, so if you’re a tinkerer, you may still prefer the iDAC6.  But if you’re simply after the best single sound possible from your DAC, the Yggy wins out.  It does everything the iDAC6 does, but adds in a bit more space and detail.  That isn’t a slam on iDAC6 is, Yggy is over twice its price.
 
Overall final thoughts
 
I like this DAC a lot.  I bought it.  It’s my favorite Delta Sigma based DAC I’ve ever heard, by a pretty fair margin.  I’d call it highly dynamic, very detailed, spacious and neutral with maybe the slightest hint of warmth.  While it is dynamic, the smoothness keeps it from being fatiguing, unless it’s also paired with an exceptionally punchy amp and headphone.  And even then some people may still love that sound.  With most amps, it adds an often looked for sense of punch, smoothness and warmth compared to most other DACs in its price range.
 
In the end, I think the $999 price is fair.  It’s not in the land of stupendous values, like say, the Schitt Modi Multibit.  But it certainly isn’t overpriced at all, you get what you pay for and a little bit more.  I think this would be fairly priced up to about $1500-1700.  So, it’s a good deal at $999.  There isn’t another DAC at $1000 or less that I think clearly beats it.  Some DACs offer something different, but nothing that I can look at and say “this is clearly better.”  It’s not until Yggy that I can point to something and say “yeah, that’s just definitely better.”
 
For me, personally, I am considering selling mine.  Not because I’m disappointed with it at all, it just sits in a weird position for *my* setup.  With my amp, it’s a touch more dynamic than I really ideally want.  The TorpedoIII amp in my system recently had an upgrade called output constant current supplies; after this upgrade, the TIII took a fairly massive leap forward in quality and became a more dynamic, harder hitting amp.  Before this upgrade the iDAC6 was ideal for my HD800 rig.  After, I wanted a tiny bit more detail, and a tiny bit less dynamicism out of my DAC.  This has me leaning towards GuMBy.  I currently have the iDAC6 in my secondary setup feeding the HiFiMan EF2C, which is a bit of an odd pairing.  My main pairing is the Schitt Modi Multibit feeding the TorpedoIII.  My long term move is likely moving the ModiMultibit to the secondary setup and side-grade moving the iDAC6 and buying a GuMBy.  I think the GuMBy’s softer, slightly more detailed profile may work better in *my* setup.  However, again, I want to stress this isn’t a want for quality, but a bit better system synergy between DAC and amp, given my headphones.  To be fair to iDAC6, I even thought Yggy was a bit too dynamic in my setup, GuMBy seemed *just right*. (thanks to Sorrdje for helping me think through this, btw).
 
That all being said, I also like this DAC so much that part of me is considering keeping it, just in case my future system takes another direction, and I again want this slightly warm, very detailed and spacious, highly dynamic sound from a DAC.

 
When i first got the Cayin iHA-6 and iDAC-6 combo and paired it with my HD800S, i wasn't too thrilled. Compared to my previous HDVD800, there was more detail present from the dac, but it came with some extra brightness and a general sense of being a bit overemphatic. It sounds thin, the soundstage is small and the treble is not well-integrated in the mix when starting from cold.
 
It's now a month later i'd the units have around 100 hours on them. What i find now, after regular use and long listening sessions, is that the combo warms up and peaks 6 hours in.
 
The difference in sound quality after the dac tubes have completely warmed up, is nothing short of amazing and revelatory. It's like a flower blooming and revealing it's inner essence. It truly shows you what this Cayin stack is all about. All it requires is a bit of patience.
 
After 6 hours the tubes provide the warmth and depth that makes the music full, natural and liquid. The soundstage opens up and positioning is improved and very convincing. The overall tone is buttery smooth natural with slam and dynamism and detailed highs, which are held in an iron grip and kept it in a straight line. The whole presentation is extremely balanced and i can't point to any sharp edges or any dullness. It's simply alive and groovy. 
 
I've previously owned the original HD800 the HDVD800, but then switched over to this setup. Even with the HD800S, i felt that i might need another headphone to compliment it. I don't have the need anymore. After discovering my setups full potential, it has made my HD800S a genre master. Something i thought i'd never say about this line of headphones.
 
This is the only setup i've been satisfied with over the years. It's my end game.
 
Nevertheless i'm in a financial situation where i have to sell it, since i'm moving out. I'll definitely pick up something similar when i'm settled in my new home. There's no way i'm going to have any setup without a pair of HD800S at least. 
 
I'm not saying the Cayin's are the only good option for your HD800/S, as there are certainly others, but at it's price, i consider this an exceptional value with high end performance.
 
It's no wonder that Cayin chose the HD800, when shooting pictures of their stack, as they both look and sound great together.
 

Cayin iDac-6 and iHA-6​

 

Prequel​

 
Let me rewind just a tad before we begin. I am one of many who interminably chase the "perfect" sound. Saying that might make it easy to understand how joyful I get when trying out new products. I always keep my radar on for a resonating blip of new gear and new manufacturers. I have progressively had my eye on Cayin as a company and with their unique DAP designs, friendly staff and great reputation - How could you not!? Cayin is a Chinese company really pushing for the western market and who's to blame them? My only experience with Cayin's products before now was a quick listen to their Spark N5 portable audio device which really impressed me. I actually owned a much more expensive DAP at the time and I truly thought the N5 was much better for much less money. Ever since this moment, Cayin has transitioned to the back of my head and nestled there until my thirst was somewhat satisfied with their new desktop duo. Cayin was kind enough to send me their iDAC-6 and iHA-6 for a listening period to review. After some listening sessions I will wistfully return both products.
 
 

Initial Impressions​

 
So right out of the box, I picked up the DAC which felt very robust and satisfying in the hands. A compact device with a sleek, modern and professional look. It feels heavy in the hand despite being small, which can be credited to the premium metals in the design. Running my fingers across the three option buttons in the center give a rather loose feeling, but nothing significant. The large knob on the right front panel has a black center and looks to be a nice matching metal and plastic addition to control volume and menu options. The headphone amp was right underneath in the box and pulling it out was almost an identical experience. Premium feel and matching color scheme and build material. A slightly more populated front panel with not 1, not 2, but 4 headphone outputs. Although these are two separate products, Cayin's marketing and even the products themselves simply yell "dynamic duo". It's a very stackable and compact arrangement of gear which look superb on a desk while not taking up much real estate, which I believe was the whole concept behind their creation in the first place. This also led me to combine my review instead of separating them, but as you'll see later on.. You can still enjoy these siblings individually as well. 
 
 

Technology & Design​

 
Cayin iDac-6: A particularly unique DA converter is the iDac-6. Right from the beginning I was very interested in this desktop device for many reasons. The most obvious reason being, like the iHA-6: a small form factor and quiet but pleasing appearance. The standout attribute for the iDac however is the integration of tubes. Tubes glorious tubes! Before we jump into that lets go over the specs:
 

As you can see, this DAC is fairly impressive from a technical standpoint. To be fair however, I will say that it is increasingly more common to see great specs from much cheaper devices these days. It isn't rare at all to find dual dac chips slapped on a PCB with low distortion, DSD compatibility and a few gimmick features. Essentially that is exactly what is going on with Cayin's iDac, but with a few more unexpected bonuses such as a user selectable tube stage option (on the fly) and a few other things that slightly set it apart. The chips used are the AK4490 which is a very good chip capable of beautiful sounding native 2x DSD as well as up to 32bit/384khz PCM.
 
Having owned many DACs in the past, I have a lot to compare the iDac to (both from memory and in person). The thing I like most about both of these products are their size. I think this is the smallest high end DAC that I have had the pleasure of using. It is really appealing for people who listen to music at work or on a desk at home as the small footprint barely uses any space. It looks very nice without standing out and can plug right into your laptop - while coworkers or family members gaze in envy. I should also mention that I like to use Linux as my operating system on my computers and one thing I will thank Cayin for is its compatibility. Usually it is always "plug and play" with most products, but recently I have run into problems with a DAC not being compatible - so it is worth mentioning that the iDAC-6 works flawlessly with Ubuntu and Linux Mint.
 
The iDAC-6 has RCA outputs as well as 3 pin balanced outputs. Standard USB type B port, coax, AES and optical for your inputs.
 
One feature I would have liked to see here is a power-save option. Although the four 6N16B tubes integrated in the DAC have a long-lasting 10,000 hour lifespan.. I would like the peace of mind knowing I could offer a more optimized and energy efficient quality of usage. I tend to do most of my listening at night and I have fallen asleep more than once while leaving one of my tube amps turned on. It's just a bad feeling, no matter how insignificant the overall affects are. My McIntosh MHA100 actually has this feature built in and it is a pure solid state device. I like knowing that if I fall asleep or forgetfully walk away that my headphones and amp won't be constantly running for hours or days. For the record, you can easily turn this off on the MHA100, which you may want to do if you were looking to burn in a new pair of headphones.
 
Overall the specs are great and the implementation of the quad tubes make for a uniquely magical fully balanced machine.
 
Cayin iHA-6: Here is what I could find for the specs on the iHA-6. It should be noted that it is really hard to find any official documentation regarding these two products. It looks like they haven't yet been added to Cayin's official website yet and I guess them being so new contributes to the lack of information online.
 
 

 
Another case of expectedly pleasing and common specifications. Low distortion and a frequency range well beyond our hearing capabilities. I like the fact that you can choose to have a lower or higher gain setting. This amplifier will certainly give you the juice needed for power hungry headphones being 7W @ 32 ohms as well as accommodate the more efficient headphones or in-ears. The design, just like the DAC, is sturdy and premium. A sandblasted metal housing (which should also help with EMI resistance) surrounds the inner workings. The iHA-6 gives the option of balanced or unbalanced, but the jump from an output impedance of 10 ohms (low) to 120 ohms (high) is slightly off-putting. Coming from a McIntosh MHA100, I had the luxury of 6 different options for matching the power perfectly with what I was using. My Grado RS2e for instance is somewhere in between the two settings of Cayin's amplifier and I felt a little uncomfortable using either low or high. The balanced output however is a much better story. I found myself using it almost exclusively in balanced mode using my LCD-4's and boy did it power them pleasingly. Balanced has a mere .3 ohm output impedance which really makes it perfect for almost anything.
 
 

 
 
Conclusion: The overall technology and design did not leave me feeling like it lacked anything in particular and in fact I felt a little pleasantly surprised. I love the modern aesthetics and the hybrid tube design in the DAC is especially neat. Both make for a fully balanced solution in a small form factor with more power and features than you'll know what to do with. The only thing I would like to see from a design standpoint is perhaps sturdier feeling knobs and buttons and technology-wise I think a power save option would be a nice extra bonus. Perhaps having better impedance matching would be nice, but honestly my RS2e and even a few of my IEMs sounded just fine with the right volume. Pretty, potent and plentiful.. thats the name of the game with these two. I think Cayin did a good job making these look good and filling a niche in the market. I had some gripes, but to be honest both devices have more features and options than most of their comparable counterparts. I think anyone would be proud to display these two atop their desk or rack.
 
 

Sound & Pricing​

 
Sound: Let me start off by explaining a few important things. I am definitely an objectivist and one of those guys who blind tests before making any outstanding judgment or recommendations. To me, a DAC is certainly one of the last things I would look for when upgrading my sound. I even have trouble distinguishing most amplifiers, especially those which are solid state. That is not to say I have bad hearing either - my ears test rather well and I can usually hear hiss/distortion extremely easily (especially with IEMs). This quality is stressed even more when paired with the fact that both the iDAC-6 and iHA-6 have a very neutral and uncolored sound. I do however think they perform exactly how they should in the fact that they let the music speak for itself. There is no crazy distortion or internal DSP going on with these devices although you do have the option for a handful of filters on the iDAC, as well as a tube stage. If I am being honest though, the tubes were a slight disappointment. When swapping back and forth using an RCA connection (again the only way to do both tube and SS), it was extremely difficult to notice the difference - and this was with me swapping them myself! When doing it blindly I especially had trouble recognizing the filters and tube stage affects on sound. This can be considered a good thing to a lot of people though. If you just want a very transparent and accurate sound signature out of your gear then this is exactly what you want. When listening to my LCD-4's I noticed very good synergy. I think the LCD-4 is a pretty warm headphone and paired with the neutral and open sound of Cayins amp/dac combination I found myself really enjoying the results. The total lack of coloration with the tubes sort of begs the question though. What is the point? I know most people would want to buy a hybrid DAC for the slight musical distortion, but it was extremely hard for me to hear much if any of that at all. These impressions aren't to sound too critical however, because I did do some interesting comparisons and mismatching which left me actually pretty satisfied.
 
 

 
 
LCD-4: With the combination of both of Cayin's offerings I thought the sound was very good actually. I definitely have used these LCD-4's with some world class components and I didn't feel like I needed "more" of anything. I found them driven quite well using the four pin balanced connection and even used the HIGH level of single ended configuration with satisfaction. The only time I felt them needing more juice was when I experimented with the LOW port, which obviously isn't meant to drive power hungry planars. The bass was nice and punchy, mids were accurate and detailed and the highs were crisp. If I used some imagination I could call the signature slightly cold, as you expect that warm enveloping sound from the tube stage, but you never really got that. However, because these Audezes already give you a very laid back sound to begin with, I thought the pairing was just fine.
 
RS2e: I really love my Grado RS2e. It really is a great sidekick for the LCD-4 in that they have a differentiating sound and at different price points. Listening to the duo with my pair of Grados was another positive experience. Gregory Porters latest album really had me respecting these little devices more and more. With the RS2e's I did feel like I heard a little more of the lushness seeping into the midrange on the tube setting. The bass seemed slightly more euphonic than I had remembered it being and the midrange was very impressive. I tended to use the LOW single ended option with these headphones and I did have to turn the nob up slightly more than you'd expect, but it definitely drove them as loud as I would want them and still with decent headroom. I liked this combo a lot.
 
Compared to McIntosh MHA100: So comparing to my main setup, the difference was pretty clear. Now I will say that the MHA100 retails for about double the price of these two, so the comparisons are to be taken with a grain of salt. The MHA100 is a solid state amplifier that sounds like one of the most "tube sounding" solid state offerings I have ever heard. I think McIntosh really used some heavy filtering and tweaking, because this device sounds nowhere near neutral or cold. I happen to love this amp/dac combination from McIntosh a lot and for many different reasons. When swapping to the Cayin units I immediately missed a few things.. The bass gain option, the darker sound and the powersave feature. I think the features on the MHA100 outshine Cayin completely here and I haven't even mentioned the proprietary analogue crossfeed that give a speaker-like representation with the MHA100. Looking at purely the sound I will say both are different, but good. If you happen to prefer an uncolored, unmodified amplifier and just want a great, detailed and accurate sound then I would definitely look at the iHA-6. It sounds very much how a high end solid state amplifier should sound.. comparable to something like the Auralic Taurus or even Schiit's Ragnarok. I found myself grabbing my darker sounding headphones when listening to the Cayin duo and my brighter Grados with the McIntosh. The solid state amplifier coupled with the tube DAC create a sort of detailed musicality that really bring my headphones to life. It is sort of ironic how a tube DAC sounds a lot less warm than the solid state MHA100, but that is what I have found through the comparisons. I would only say that the unique features in the MHA100 outshine Cayins offerings, but the sound itself were almost equally enjoyable and impressive albeit slightly different.
 
Compared to LH Labs Vi Dac Infinity: I actually pretty much enjoyed both of these the same, if maybe the Cayin duo more. Both amplifiers can power just about everything I throw at them with pretty impressive headroom. The Vi Dac is again about double the price, but sound-wise I believe it is very easily in the same league as both the iHA-6 and iDAC-6. If anything I think the filters and tubestage options on the iDAC made it a lot more impressive. I certainly found the filters almost inaudibly different, but they were slight enough to make things interesting. Features in general wasn't even a contest as the Cayin combination have many more options and outputs. I should mention the size as well, because the Vi Dac Infinity definitely isn't something you can just slap on top of a desk easily. It takes up a lot of space and looks slightly out of place amongst non high end audio components. You can stack Cayin's combo right on top of almost anywhere and the subtle but sleek appeal serves as a very versatile complementation. The sound is very similar and both have fully balanced architecture. The only real difference is the variation of DAC chips as I believe the Vi DAC uses reference Sabre chips. My few select DSD files also played natively on both devices as well. I think I would recommend saving your coins for something else and going for the Cayin units if it were a choice between these two. Really great stuff from Cayin!
 
Cayin iDAC-6 with MHA100: As I am one to mix and match and try new things - it was inevitable that I tried pairing some of my components with their gorgeous Chinese counterparts. I think the best experience I had with reviewing these devices was when I paired Cayin's DAC with my McIntosh MHA100. The sound was great and I got amazing options combining the two together which made for a really nice experience.
 
 

 
 
The ever so slight lushness of the tubes seemed to be a little more apparent when combined with the McIntosh as the pairing made both sound a little warmer and more enjoyable than I had remembered. Having several different filters and gain on the iDAC, along with the tube and solid state options made for some really nice experimentations. The MHA100 has bass boost options of up to +12dB at 40hz and an analogue crossfeed that make for a ton of fun with Cayins DAC. At the end of the day I much preferred this combination and it made me really consider getting the iDAC for myself to go in my system permanently.
 
Price: The price of both the iHA-6 and iDAC-6 are about $1000 USD each. I think both of these products fill a very specific niche in the market and the prices kind of ride the line between high end and mid-fi. I think these devices aren't overpriced for the performance and craftsmanship offered, but I think Cayin would have sold a lot more units if the price tag was slightly shrunken down. Overall you definitely get what you pay for and I think the pricing is probably more than fair.
 
 

Closing Thoughts​

 
I really enjoyed my time with both the iDAC-6 and the iHA-6. The best situation for someone to buy these is if they have limited desk space or don't want huge devices getting in the way.. all while gaining a modern stylish look of audio products with excellent sound quality and a few niche bonuses such as a quad tube DAC. I didn't mention before that these little offerings pair well with a broad selection of IEMs too. My Kaiser K10's especially were driven correctly and sounded as perfect as they ever had. I only very faintly heard a whisper of hiss-like distortion due to the sensitivity of the K10's, which is completely expected. These are very versatile, sound just as good as much more expensive equipment and I think anyone would be proud to have these in their inventory. Well done Cayin!
 
 
 
 
-Writing and review by Dillan-
-Photography by Regan Hulvey-

Tour Unit Disclaimer: I'd like to thank Cayin for letting me have the opportunity to get a chance to demo the iDAC-6/iHA-6 stack for a week. However, I need to point out that I do not own the unit personally. The stack will be sent on to the next tour participant at the end of the week.
 
Note: Please note that this tour provided both the iDAC and HA as a stack and this review is looking at both as a paired unit. However, as mentioned below, I found that the iDAC stands alone quite nicely.
 

Initial Thoughts

While this TOUR stack looks and fits great on my desk and more importantly sounds great, it is not my preferred signature. The SQ is top notch, but tends toward the bright end of the spectrum conflicting with my brighter headphones. The treble shelf also interferes with dynamics as it forces me to turn the volume down as higher volumes are just too bright for me. The exception to this is my LCD2.2 with which it is a great pairing given the LCD’s warmth and was the pairing I stuck with. My second favorite pairing was my Hidition NT6pro CIEMs which brings out Cayin’s dynamic capabilities nicely even at lower volumes. Don’t get me wrong, the HD700 and HEX sounded great with the stack, but I was forced to listen at lower volumes.
 

LCD2.2 Pairing

Listening with my LCD2.2, I found that the Cayin required warm up. Leaving it on was not good enough, it needed to be driven hard. The hotter the Cayin stack got, the better it sounds – and yes, it could warm a room when driven hard. Getting warm, my preferred euphonic style signature came out. The LCD2.2 also allowed me to turn up the volume to optimize sound stage and dynamics without sounding loud/bright. This led to several evenings of hypnotizingly good SQ where I could listen for hours. In general, the sound stage when optimized becomes very deep with good layering/separation/transparency – but this is not a sound stage junky’s setup as it is fairly narrow. However, I did not find this bothered me and enjoyed the depth very much. I spent little time playing with the settings finding that I could only hear a difference between the transistor and tube settings with the tubes sounding better – so I left the tube setting on for the remainder of my listening. The tube setting again needed the stack to be hot before the difference was easily realized – cold they didn’t have much SQ differentiation.
 
The AK4490 sound was recognizable from my AK380 and Aune M2 listening sessions having great detail and instrument placement. I will be picking up the Aune M2 for my LCD2.2 as it had the same pairing results going portable. While the sound stage was roughly the same as these DAPs, the perceived width for a DAP seemed larger vs. competition where the desktop competition is greater. However, the SQ is definitely TOTL, just tilted toward bright/analytical vs. my preferred euphonic tube-like preferences – except when paired with the LCD2.2.
 

Comparison

To check the DAC capabilities, I paired it with my Eddie Current Black Widow to see how it compared vs. my Havana 2 tube DAC pairing and it did great.

1. BW vs. HA: The EC BW amp is definitely a big step up from the HA-6 in terms of my preferred signature and added a lot of weight to the notes as well as a little width to the sound stage. The BW also enhanced the inner detail provided by the AK4490 making minor textures more audible and felt. The bass took a large step up as well with more textures and resonance. The BW is a better pairing for my preferred signature which is obviously the reason that I purchased it.
2. Havana vs. iDAC: Against the Havana 2, the iDAC-6 felt much more detailed while the Havana felt more euphoric. However, the width of the Havana provides more transparency/sound stage to balance out the equation – so they are different rather than better. However, I am really diggin’ the iDAC/BW combo with the LCD2.2 and would be happy keeping that combo.

 

Value

The Cayin stack is stunning and absolutely looks like a $2200 stack on my desk and I very much appreciate the ease of use. However, for that money and already owning the BW, I feel that there are other options that would be better for me and my personal needs. However, another important consideration is that this perfect looking stack is also kid friendly where my stack requires strategic hiding under my desk. That means that the Cayin would be used where my current setup does not - that is worth a lot too. There is a big value to me for having something that I don’t have to hide and can be proud of which also simplifies its use.
 

Conclusion

The Cayin stack is a win in my book. For those that love the analytical signature and the AK4490 TOTL SQ, this would be a slam dunk. Overall, I am sorry to have to let this stack go as it is much easier to use than my EC BW/Havana 2 stack which has been sitting unused. Having said that, I am going to go back and listen more until I have to part with this tour unit.

All righty then. Impressions for the iDAC-6 and iHA-6.


Disclaimer:
I'd like to thank Cayin for letting me have the opportunity to get a chance to demo the iDAC-6/iHA-6 stack for a week. It was really a pleasure to get a chance to hear it more carefully outside of a local Head-Fi meet. This review will focus on the iDAC-6 since I probably needed a more diverse set of headphones to really get a good listen of the iHA-6. I did write a few impressions for the iHA-6 here though if you're interested.


The super short summary:
I love the iDAC-6!

Value: 4.5/5
Audio Quality: 3.5-4.5/5 depending on the sound settings for me
Quality: 4.5/5
Design: 4/5
Total: 4.125-4.375/5














About me:
Since I acquired the STAX SRS-2170 in 2014, I've been exploring DACs a lot more since I no longer needed to search for an amplifier in the traditional sense. From the past few years of the hobby, only the LH Labs products, Audio-gd, as well as the Schiit Yggdrasil have left really positive impressions for me in terms of sound. I opted for the LH Labs products via their Indiegogo campaigns since, I'm guessing this is true for many crowd-funded campaigns, the idea sounded really nice on its first presentation, and on-paper. I'm not dissatisfied with their products for the most part, but they do have a sigma around here. The Yggy came out after I received the Pulse X Infinity DAC/amp anyway, and I didn't want to shell out a few grand for a DAC that couldn't fit on my desk and takes a week of on-time to sound at its best. But theeeen...




Enter the iDAC-6:
At $999, I think this DAC is an absolute steal for the money.

• It can play back pretty much any digital audio track you throw at it (16/44.1 to 24/384 DXD to DSD256)
• It's a fully balanced design so it gets the benefits of differential signaling
• It has a myriad of sound options you can switch to
• Versatile input/output options

The volume operation is similar to that of other multi-bit Delta-Sigma DACs I've seen, meaning you can use software or the volume knob to control the digital volume level (only on the pre-amp mode). Alternatively, you can set it to line-out mode, which is a fixed volume level (or basically maximum volume). It has the option to decode DSD in a true 1-bit fashion, but from the description here, it looks like that's only possible through the coaxial digital input and not USB?

Anyway, I was using the USB input and I used the iFi micro iUSB 3.0 with the LH Labs LightSpeed 2G cable.

The DAC chip itself is the Asahi Kasei Microdevices' AK4490. Most of the DACs I've heard use an ESS Sabre DAC of some sort, so hearing a well-implemented non-ESS DAC was a nice change of pace for me. I had previously listened to the iDAC-6 at a local Head-Fi meet, but it was paired with the iHA-6 on a different setup from my usual environment. Because of this, I didn't know what the iDAC-6 would sound like on my system and boy was I surprised. Its overall sound is super smooth, balanced, punchy bass, and natural-sounding overall. Absent is the the "Sabre glare" brightness that I'm used to hearing from ESS DACs. Even though I find the Pulse X Infinity to greatly reduce that sound, comparing it with the iDAC-6 made it really apparent to me that it's still there. The soundstage presentation and imaging of the iDAC-6 sounded pretty spherical to me, having about equal dimensions of height, width, and length, but it was on the smaller side to me. Instrument separation was likewise good, but not quite up to spec with the Pulse X Infinity.

The one major negative experience I had with the iDAC-6 was that it includes muting relays(?) inside of the device that activate whenever audio is stopped being transferred to the device (you can hear the unit making clicking sounds when this happens). When audio is resumed, it takes half a second for the relays to switch off, which means you will get a delay in audio to your speakers/headphones. Especially for watching videos and/or editing audio, this is a really annoying thing to have since you would need to rewind the video/audio track few seconds to get back to where you left off.

In terms of the different sound options you can toggle with the iDAC-6, I preferred the "transistor" setting over the "tube" one since the "tube" one sounded a bit more like the ESS DACs. Compared to the Pulse X Infinity's digital filters, I had a harder time picking out differences with the 5 filters offered in the iDAC-6. I preferred the sound with the "S.D. Sharp" or short-delay sharp digital filter over the other ones as it sounded the smoothest to me and the imaging was more well-defined. "Sharp" was the next best for me, and I somehow didn't like any of the 3 "slow" filters since they, coincidentally, sounded sharp and biting to me.

From my limited knowledge of digital filters, the "short delay" filters might be minimum phase filters in which the pre-ringing energy of transients is delayed until after the signal. These types of filters are usually seen in "fancier" or more expensive DACs, so having them in this $999 DAC is really nice for users to experience. Minimum phase filters are often associated with sounding more "natural" and having more precise imaging. As for "slow" versus "fast," I'm pretty sure that indicates how much the digital filters attenuate signals at the Nyquist frequencies: "slow" meaning it allows some aliasing signals to enter the passband frequencies past the Nyquist frequency at the convenience of having less ringing occur in the impulse response; "fast" meaning it attenuates signals very close to the Nyquist frequency at the cost of having much more ringing in the impulse response. Typically ringing is bad, as is pre-ringing, so it sounds like the ideal filter would be "S.D. Slow" or short-delay slow. I haven no idea what the fifth filter does though, "Super Slow."


Conclusion:
Considering what the iDAC-6 sounds like, what it can do, the versatility of inputs/outputs it has, how much you can change its sound, and its price, it would be hard for me not to recommend this fantastic DAC. If I didn't already have a good DAC system with me, I would probably buy the iDAC-6, and that's something that doesn't happen to me often. If you get the chance, I would highly recommend giving this a listen!



[rule]
Just some general gripes:

• The iDAC-6 gets really, really hot. When I was packing them up to give to the next person on the tour, I turned off the units and tried to pick them up after waiting a couple of minutes. Holy, they were still burning hot; like trying to hold a single-cup hot Starbucks coffee without a cardboard sleeve.
• The corners of the unit are pretty sharp, just F.Y.I.

Thank you Cayin again for letting me be a part of the tour!

CAYIN iDAC-6 & CAYIN iHA-6 ​

REVIEW​

Intro

While Cayin to westerners have been more known for their portable gear lately, they have been making serious DAC’s, CD players, and speaker amps for a very long time. A while ago I had purchased from a website the Cayin HA-3. It is a DAC/AMP combination with tons of power and a small tube inside. I had really enjoyed that piece of gear and it lasted in my stable for quite some time. I wanted to review it but didn’t believe it was appropriate because I had the the wrong voltage and had to use a step up transformer. Without being aware of how much of it’s sound quality was being affected by the situation I just kept most of my impressions under wraps. Quietly, I was very much on the look out for new desktop equipment from Cayin and since they had won me over with their portable C5 I had really nothing but high hopes for the Chinese manufacturer. If I could place a house sound on them, I would pretty much say they like clean, and clear, but musical which is something most of us can appreciate. Fast forward to now and I have been privileged have a chance to hear their latest desktop solutions. 
 
These units go so hand in hand, with so many similarities, that a separate review for each one would seem a little repetitive to me so I would rather combine them.  
 
Both units are meant to be reference quality. As with the previous products, they intend to punch high in performance without raping your wallet; yet this time they desire to add value in features as well as sound quality. Are they successful? Well before I make a judgement call on such serious pieces of gear, let me be acquitted from any thoughts you may have of me being a seasoned “know it all” audiophile. While I have been fortunate to try a lot of gear, I mainly go for what sounds right to me as most of us should, since personal audio is so…personal. 

 

BUILD, FUNCTIONALITY, AESTHETICS & SPECS

 
These little suckers don’t take up much desktop space at all but are imposingly dense little masses of solid construction. The substantial chassis is made of an aluminum alloy with all of its bolts and screws (the few that there are) hidden underneath the units and in the back where all of the interconnection takes place. Conveniently, the power buttons are on the front which is a  simple but no-brainer placement that for some reason a lot of manufacturers refuse to incorporate. Around the power button is a neon-whitish-blue light that lets you know the units are powered on but have a safety feature of blinking first before its ready. The knobs are both wonderfully sized and similar to all of the buttons on the faceplate are of a shiny finish. They rotate with a polished and smooth resistance on the i HA6. Dialing in your ideal volume is as easy as it gets. The i DAC -6, though similar in appearance, has a knob that rotates with less resistance but soft clicks to enable exact option selections since it is a dual functioning component.
 

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CAYIN iDAC-6

The DAC uses two AK4490 chipsets and each chipset will work for for a single channel. It is a truly balanced DAC that fully exploits the potential of both chipsets, which when researched is supposed to have less distortion and yeild great results compared to ESS sabre chips etc. More can be found on the matter here (https://hifiduino.wordpress.com/2014/12/07/akm-verita-4490-dac/). There are 5 digital filters that you can use. Inside are also 4 6N16B vacuum tubes at the buffer stage that work when using the DAC in balanced mode and RCA mode. While using balanced outputs it only uses the tube out put stage. 
 
It is highly versatile allowing one to select just about every option of inputs. The OLED display will reflect your choice of options. 
 
layout:

From left to right - 
You have the previously mentioned power button. There is a OLED screen that displays your various selections. Underneath that LED screen is a Source button, Timbre button, and Line/Pre button. To the right of that button is a volume control if you select the ‘Pre’ function.
 
Options:
 
SPECS:
 

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CAYIN i HA-6

The amplifier is of a quadruple circuit with fully discrete components and a fully balanced design with independent power supplies to each channel. It is designed to not only be capable of powering any headphone with a lot of headroom, but also properly match various impedances making it an excellent all-in-one solution. Even sensitive earphones will yield little to no noise when music is not playing. The iHA-6, simlar to the DAC-6 has been designed with practically everything taken into consideration. Literally all I could ask for would be a bass boost button on it but that is not really standard on desktop gear this serious. It’s small footprint size, solid build, and tons of power make it  almost the ideal amp for just about any situation on paper and in practice. 
 
Layout:

Left to right-
The power button is on the left and right next to it are the source (balanced and unbalanced), Current, an Gain buttons. In the middle are three headphone jacks: Balanced left (also for low impedance headphones), a Balanced Right (for High impedance heapdhones), and a 4pin balanced connection. To the right of that is the volume pot which rotates with a very smooth resistance that enables you to easily find your listening level. 
 
Specs

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 ​

LISTENING IMPRESSIONS​

 
During my listening I did get to pair the DAC with some other amps, but for the most part I had the iHA6 hooked up to the i DAC to get a really good impression of thier performance together. These units are obviously intended to be paired together and sonically they match each other in what seems to be an inseparable marriage until the end. The high-end or 'reference class' market is a tough place for a manufacturer to enter into. Not only are most audiophiles buying gear to get the most from the recording but undeniably find pleasure in picking apart the sonic attributes of the gear before them. I recently had some close friends over for dinner and as I explained to them how much the headphone gear costs on my table they had a hard time pulling their face muscles into conforming to their normal expressions. They were not only surprised by the price but also the sound. The reality is that to the already underwhelmed but ‘high-fidelity’  acquainted listener who usually has a lot of high maintenance demands, being wowed is a rare treat. Needless to say, the stack has it’s work cut out for it. But just as the above build quality is very much to and possibly above standard for its price, so is the sound quality and I pretty much place bets on it not wowing the listener but bringing them into the reality of what they should be expecting their gear to sound like should they venture to or beyond this Cayin stack. 
 
Basically, a great point of reference is what this set up is. The moniker ‘reference’ denotes a standard of fidelity and tuning that can be used to judge others by. Plugging my headphones into them for the first hour was a relief because I was hoping it not only looked clean and professional but sounded so. Have you ever seen a person walking a dog and the dog looks just like the owner? Well I picture Cayin representatives to be dressed up in a suit but with a cocktail in their hands. Sharp (acute), slightly edgy with pizzaz, serious, but able to take a joke or two. 
 
Listening to Flying Lotus’ - “Until the quiet comes” through the balanced out and HD800S was about as thin, splashy, and non-pleasant as it gets but either switching the song or the headphones made a lot more sense. That song is poorly mastered with way too much sibilance but switching over to a more forgiving headphone like the Kennerton Vali’s  and they owned that song with a very tight and clean bass hits, lovely midrange balance that is neutral but not too thin with a precise timing that while a little on the fast side is neither too offensive or high-handedly harsh in tonality. 

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iDAC-6

Most recently I have had the revelation of the transparent yet analog sound of non oversampling DACs. In a recent shoot out between my Geek Pulse Infinity in the 1.0 chassis and matching LPS vs the Stockholm v.2 I found the cheaper NOS DAC to out perform it in realism. It brings the vocalist not only closer, but clearer with better dimension. I quickly sold my pulse infinity DAC and purchased an MHDT Stockholm v.2 because there seemed to be something of a digital wall in between me and the music where as the Stockholm freed up the music to be more realistic. I will not confess the ‘6’ to sound more euphonic or natural. In fact both of theseCayin units are on the more neutral and precise side of the coin, however the music sounds unhindered and clear. So much so that I would count on it winning me over just as much as the Stockholm did but in a different way. While the NOS R2R DAC warmed me up to the music it lacked a bit of precision and the bass was not nearly as controlled. Though I can depend on the iHA-6 to produce a solid low end the iDAC-6 is just as responsibly free of trimmings usually associated with over-extra warmth. Looking back at that set up and the MSRP of the pulse infinity and LPS vs the i DAC here with me during this time, I can say with full confidence that this is the more complete set up. The i-HA6 will literally laugh at the balanced headphone amp of the pulse gear and the iDAC is more transparent overall and from memory when I used the Stockholm as a point of reference. Please forgive me in advance for not separating the inseparable through-out this review. 
 
The iDAC-6  in comparison to my similarly (slightly more expensive ) metrum acoustics musette: Like mentioned before and after this I do really appreciate what R2R DACs bring to the table in regards to natural tonality yet in this case I actually prefer the iDAC-6 for a few reasons. If a DAC is too warm or a little overdeveloped in the midrange and not fast enough by even just a little, it can mask the intelligibility of a voice or texture of an instrument. I personally prefer the Metrum musette’s smooth treble but even more so prefer the Cayin’s speed and neutrality in the midrange. Ideally I would prefer somewhat of a middle ground or the marriage of their individual strengths but when forced to pick it is the i-DAC 6 just slightly. The Cayin renders music less biased and  sounds more flat but forces the details more with a slight tendency towards edgy in comparison while never really crossing over. The cayin also also gives a little more  ‘hear through’ factor for the recording but does sound a little less analog. Part of the reason the metrum may sound slower though is because it is reported to improve with a better power supply.  Pairing the Musette with the Cayin iHA6 did make for a more inviting sound and is less fatiguing overall and with the HD800S it was more ideal than the Cayin duo all things being considered without losing too many details. Take the Kennerton Vali  though, and the iDAC-6 basically made that headphone a dream whilst the Musette added that extra midrange warmth that for even a midrange lover like myself found to cripple the headphone.
 
The DAC is decently spacious but don’t expect a super deep or wide image. Instead expect to hear a clean and transparent rendering of your music that is a little less warm and graceful than it is tidy and resolved. It has a good, clear treble, neutral midrange, and tight bass.  
 

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Both

I did take the HD800S and use the timbres and filter adjustments to try and mimic what plugging it into my tube amp would do. DAC filter settings usually yield small differences. The differences were sensible yet subtle enough to be practical. Of course it is not enough not turn it into an HD850 or anything close. No matter the current setting, the timbre setting, or the filter setting you still have a bright set up. Even though the treble texture is neither hard, glaring, or grainy yet clear with all of the details present. I much prefer tubes on this headphone and would love to see how the Cayin HA-1A MK2 would pair with it. I would say that Cayin’s new desktop solution is very detailed but not brutal. I recall when I had the HA3 receiving a pm from a gentleman who asked me if it had the signature “CAYIN Sparkle”. I told him it did a little bit but this may be more up his alley and If I were him looking for a total package I would not look further. 
 

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iHA-6

The iHA-6 amp is very much in line with that kind of tuning. It is a powerhouse of clear and neutral sound that does everything with a touch of purity yet nothing in excess and as well performs with a neatness that matches its counterpart.
 
 The dynamics from the single ended out put of the iHA-6 are fair and it is a lot more punchy than the Airist Audio Heron 5(an amp I find too soft in attack) but less full bodied and meaty than my Nuprime HPA-9. Take a double leap up in price to my Trafomatic Head 2 and I have a slower sound that is a lot more natural, less engaging, less bright, with a similar transparency yet better with higher impedance headphones than the iHA6. The iHA6 has a lot more power, and while less dynamic and punchy, it has a slightly tighter bass with a faster, flatter, slightly edgier solid state sound. Neither are lush but they still sound vastly different. Comparing the two together really shows me how capable the iHA-6 is in some areas technically, especially in clarity. 
 
The reality is that plugging just about any headphone I had here into the balanced jack offers better pop and dimension bringing it to really gripping level of  punchiness yet still being clear with focused transients.  I have learned my lesson about a nicely built single ended amp sounding a lot better than a poorly designed balanced amp, however it truly is the case here where I believe the balanced section sounds better to my ears. I will go on record saying that this is pretty much about as transparent as I have heard an amp. My memory cannot legitimately conjure up a more  transparent piece of headphone powering. To make a ‘winner takes it all’ kind of amp Cayin would simply need to add more depth, tonal density, and attention to micro-dynamics to flesh out the recording more realistically. To recap what I have mentioned earlier about the Nuprime having more body, I neglected to mentioned in the same frame of mind that the iHA6 is the more clear and vibrant sounding amp and can awaken sleepy headphones. Surprisingly though, and for the price I would place the Nuprime as an excellent piece of gear, just outdone overall by the sincere efforts of Cayin on this one.
 
To forewarn,  I can see how someone will be fatigued during long listening sessions with the wrong headphone though as again, it is not the lyrically waxed and romantic kind of sound. There is much to appreciate about the this amp being slightly airy with good space and a benevolently graceful treble. Honestly, for a solid state amp this should be highly considered as a good endgame purchase at a great price, given you find this tuning up your alley for what headphones you have. 
 

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BOTH

Another thing to note is that switching the inputs via the source button on the DAC reveal the RCA from the iDAC-6 to sound just as good, if not a little cleaner at times than the balanced output of the iDAC-6. I have two solid silver interconnection pairs made by the same manufacturer with practically the same specs except for the RCA cables being a little longer so simply pressing the source button enables me to hear the tube output stage of the balanced section vs the single ended transistor stage of the DAC. To my ears the tube warmth is noticeable and welcomed with certain songs. It was able to slightly trim off some fatigue during some sessions. But as to be expected, the transistor stage is audibly free of that tube distortion. Also the single ended RCA’s to the balanced jack of the amp showed no loss of fidelity or volume because of it’s thorough design. This effect, though it reads like I am describing the DAC mostly, is due to the way the iHA6 takes the RCA inputs and phases the signal properly to balanced in away that will suffer no loss of sound quality. 
 
Small but noteworthy gripe: The DAC’s balanced output is tube output only.. The RCA output is the versatile output stage allowing you to use both tube and transistor. When you look at the specs above it seems that it would be more logical to have the lower distortion on the balance output stage. Based on that I would have rather had the RCA outputs be vacuum and the XLR outputs be the transistors. If  someone wanted to use a tube amp they could be possibly doubling the distortion. Though tube amps are usually single ended this may not be as much of an issue and again RCA makes sense there but some amps, like mine, have XLR inputs though they are not truly balanced. For this reason I send the RCA’s to my Trafomatic Head 2 via transistor mode. Usually a balanced amp, (not the Cayin iha-6) sounds best when being fed from a truly balanced DAC via the XLR’s but in this case you will have to hear the tube sound.
 
Someone reading this is going to think “ well get to the part of what timbres etc you used and with what headphones”. I must confess here in a little bit of a let down that though I found the slower filters to be more aggressive, I really liked to just set it and forget it at either the slow filter or the sharp one because again, while they work and do change the sound, I heard more significant changes from plugging my headphones in the appropriate socket with the correct current setting. The filters to me are more like slight changes in the mood of the same person. The individual still will be who they are but they may give the same answer with a different way of saying the same thing…close to reference. I did noticed while listening that when I had it on  the super slow filter I wanted to turn it back to slow because I felt a little more listening fatigue. 

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CAYIN iDAC-6 sum-up: Extremely versatile and precise piece of gear that is honest and is of the neutral and balanced way of listening. It is clear with and transparent with the filters and sound adjustment options slightly modifying the listening experience. It has pleasant and slightly spacious sound with good resolution and details. Slightly flat and a little bit bright for someone coming from the NOS camp but it is appreciably a clear, and no nonsense piece of gear with tight bass, and good treble texture. 
 
CAYIN iHA-6 sum-up: Very powerful and transparent piece of gear that gains some attack when used balanced. At a meet, the HE6 had ‘nuff headroom and the HE1000, while still airy didn’t sound to harsh in the treble. Since that bass is tight and controlled, it’s sound is clean without too much harshness, and it is musical without too much aggression,  you gotta respect it as a very serious piece of gear. For a solid state it has a decent soundstage and can great details, and a fast sound. 
 

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HEADPHONES​

because the iHA-6 DAC is made for this and this alone!
 
Audeze LCD2.2F
Loosely preferred: Balanced, High gain, low current, slow filter, transistor mode.
 
The Stack adds an untarnished sort of presentation to the LCD where it gains some control but for some reason loses a hint of it’s enchantment.  I felt the pairing was decent but largely preferred my Trafomatic Head 2 for adding some emotion and body to the LCD2 as well as depth. Probably not the best idea to compare a 2500 tube amp to the i HA6 but I am reaching for a reference to describe my preference(that rhymed yo!). Most will find the LCD2 to be engaging but I got a little bored of it sometimes no matter the amp pairing, wanting more macro and micro dynamics. I feel the extra helping of speed from this combo makes me loose a bit of body weight. I believe the LCD2 is balanced very well but can sound a little meshy, especially in the treble on busy songs and I didn’t really hear the Cayin helping this out. I sometimes find that while the LCD2 sounds very nicely balanced it can use a bit of attack from an amp but a lot of extra power usually doesn’t help as much as the right amp itself. Hearing the LCD2 on the Decware Taboo MKIII at put a smile on my face that would be the definite choice over the iHA6 for the Audeze. This pairing is good, clean, tight and airy yet not so magical because it doesn't assist the LCD2's lack of layers. When used balanced I experienced less of a leap in performance than with the other cans. Let me admit that most of these impressions are for a couple of reasons: One I don’t find the LCD2 super scalable as much as I find it picky, and 2 because I really had hard time preferring this combination to the Omni and i HA6 pairing which in short won my appeal even though the midrange of this combo is still the more believable.  Since the Cayin Stack isn’t a meaty, full bodied sound it is a decent pairing but I have heard better. Not really bad though and works fairly well on most songs, especially since the bass firms up a bit and the transients are clean. 
 
 
Omnis 

Mostly preferred: Balanced, High Gain, High current, slow filter, transistor mode.
 
Excellent pairing here. However, the Omnis have a tendency to sound a bit forward in the upper midrange all while placing the vocal a little distant positionally. Well, the Cayin has a slight tendency to make the upper midrange prominence of the Omni more noticeable. Where the paring excels is in the bass performance and speed. The Omni needs a lot of power for the bass to pick up in speed, and also not just power but the bass of the gear feeding it needs to be relatively quick and precise. The IHA6 and DAC6 combination deliver on those fronts without leaving any scraps behind.  Also this pairing really opens up the Omni to show how technically capable it really is. Previously, and on lesser DAC’s I found the Omni to only be decent at details, plug them into these babies and you will most definitely hear a high fidelity sound worthy of the close to 3k total(for all three pieces). Since the Omnis have plenty of tonal weight the overall richness of timbre with this combination is as lifelike as I have heard them, albeit with the aforementioned upper midrange boost. Listening to the Omnis through the balanced out of the iHA6 and the Nuprime is night and day. Furthermore I find it a much better pairing than the Airist Audio Heron 5 which has a smoother treble, and wider soundstage but is less detailed, has even less tonal weight, and much less punchy. The Heron had a preferable balance from mids to highs but the textures seemed to disappear  when going to it from the IHA6. 
 
 
Kennerton Vali

Mostly preferred: Again better balanced. High Gain, low current, low impedance jack, S.D. Slow filter for a hint of crispness.
 
The Kennerton Vali is an excellent sounding headphone on most fronts. It is pretty fast but has a little bit of extra decay so though an amp a little slower than the IHA-6 would work fine, it still needs to not not add any extra decay and be quite precise. A dry amp will actually work fine with this headphone. Dry simply means no extra decay or that the decay is unnaturally cut short and there is some trimming to be done with the Vali. The Vali has a tunefully pleasurable amount of bass that can be held back by other amps and the IHA-6’s tightness plays favorably for the Vali. The three together (6,6,KV) perform admirably in the bass with solid slams and punches. I initially thought the Nuprime HPA-9 was a better pairing, but that was for a few songs and also when the Vali is used single ended. Balanced however, the Cayin is clearly the better amp for the Kennerton. It helps it image more precisely and doesn’t hinder the soundstage, yet doesn’t really stretch it out either. I would say that amp/dac matching the Vali is pretty important and you could stop right here and have a wonderful 3 piece rig. With my Musette NOS R2R DAC feeding the IHA-6, the already euphonic Vali becomes too thick while the IDAC-6’s clean and slightly poised nature brings the Vali into a more perfected tuning, that while slightly fatiguing for the long haul in force and vibrance, is a lot harder to fault. 
 
HD800S 

High impedance, low current, right jack or balanced, slow filter, tube timbre. 
 
I actually like the clarity of this pairing and find it to do best balanced. The separation is better as so is the dynamics when used balanced. The balanced jack of this amplifier and pairing bring the dynamics up quite a few notches. I actually don’t prefer the transistor section over the of the iDAC-6 when paired with my Trafomatic HEAD 2.  It is most definitely not going to take the bright sound and finesse it up like a TOTL tube amp does but all of the spaciousness and details are not by any means held back. I would more like to think that amps that are more spacious are enhanced spaciously (to my liking) and this stack is a good reference.   I could see some calling this pairing a little thin compared to a top of the line OTL tube amp, or even my trafomatic head 2 being a better pairing since it adds more body to the lean and spritely sounding S.I personally prefer a darker sounding pairing since I think the HD800S is a bright headphone. The iDAC6 transistor mode has sharper details and when switching to vacuum, the tones still sound very similar but are less fatiguing for extended listening. 
 
Modded Pioneer HRM-7

Sounds best balanced again and does great with lo gain.
 
 This is by no means a popular headphone. It is fairly sensitive and easy to power. When turing the music off and the volume very high I heard no noise from either pieces of gear. If I can toot my own horn a little bit I would say that it is the best sounding headphone for my tastes under 300 usd. It is supposed to be able to take a lot of power before distorting and it can for sure but also at 45 ohms and a decent sensitivity it shouldn’t need high power to sound better, yet it very much does sound better balanced through the cayin IHA6. The bass is very tight, the midrange is flat and I get to hear my mod from a very neutral amp and DAC combination with absolutely no hiss or distortion enabling me to trust what I am hearing when modding these headphones.
 

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CONCLUSION​

iHA-6

After having the Heron 5 here, the Nuprime HPA-9, the Cavali Liquid Carbon, and the Infinity all around the same price and performance expectations. I can easily say that I only can legitimately say my Trafomatic HEAD 2 is above it in performance for most areas. As for the rest mentioned, this amp is the executioner; the slayer of all before it in performance and at 999USD gets a whole hearted recommendation. When reviewing things I simply say “I prefer” and don’t carry on about it being the best of this or that; or carrying on about it  taking me to another place etc etc because by nature I am more of a realist. I am really considering how, after my most recent purchase I can fit this amp into my stable as an ‘end game for now’ solid state amp since it performs so well and so clearly. I conclude it to be very much reference and is most definitely able to reach at a higher MSRP than it is listed for making it an exceptional value. 
 

iDAC-6

This DAC is very much transparent. While it doesn’t offer the deepest and most lyrically warm and natural sound it is very impartial and paired well with every amp and headphone I had it with. I am very glad to admit it doesn’t have that digital wall that my other DACs have had. It is vibrant without the hard and unnatural glare and when paired with other TOTL gear I hear still a wonderful clarity and a neutral, no bull-crap sound that is able to reveal most of what that gear can do. An individual was interested in my DAC that I had for sale and I recommended to them this one instead based on his gear. That isn’t to talk about my honesty but the iDAC-6’s because it's worth a recommendation even at my own expense. 

 

BOTH

I cannot, with a clear conscience, not recommend this  gear since they performed flawlessly for the two months they were here. Their build, price, features, design, and sound quality should earn CAYIN a solid foot hold in this tier of audio gear as I believe these entries should be referred to when people make comparisons. After waiting to hear the new Cayin desktop gear for some time I can honestly say the did not disappoint. Excellent gear for sure. 
 
Gear used during review period:
CAYIN iHA-6
CAYIN iDAC-6
Nuprime HPA-9
Airist Audio Heron 5
Trafomatic Head 2
Metrum Musette
27"iMAC 5k retina display
Apex Teton (from TTVJ)
HiFiMan He1000 (from TTVJ)
Kennerton Vali (tour unit)
HD800S
ZMF Omni
Pioneer HRM-7 Modded
Audeze LCD2.1
JVC DX1000 not mentioned but actually a great pairing
Solid Silver RCA interconnects
Solid Silver Pailics XLR interconnects