Thanks to Cayin to organize a review tour program for Cayin C5 DAC!
I've given around 2 weeks to use and observe the quality of the C5 DAC. Usually I would need a minimum of 1 month to do a proper review of a DAC, so I hope within the short period I would be able to cover all the the important aspects of the C5 DAC.
 
http://en.cayin.cn/product_view.asp?id=791
 
Some background of CAYIN model naming is explained here:
http://www.head-fi.org/t/768094/new-portable-cayin-spark-c5-dac-amp-released-may-2015/15#post_11650004
 

 
 
 

Summary of Sound Signature:

Neutral, slightly warm, energetic with good dynamic, especially for IEMs & easy to drive headphones.
 
 

Summary of Features:

1. Up to PCM 24bit / 96kHz USB DAC.
2. Multi-platform driver-less USB operation.
3. USB DAC + Headphone amplifier. No dedicated line output, so cannot be used as dedicated DAC without the headphone amplifier.
4. Headphone amplifier. There is a 3.5 mm socket analog line input to use only the headphone amplifier without the DAC (AUX mode). The headphone amplifier is quite powerful and can be considered the strong feature of the C5 DAC.
5. USB to SPDIF (electrical / coaxial) converter.

 
 

Pros:

1. Multi-platform driver-less USB operation.
2. Powerful headphone amplifier.
3. Very good battery life.
4. Very soft On-Off popping noise.
5. Carefully thought accessories.

 
 

Cons:

1. Low gain output is still too high for general IEMs.
2. No line output.
3. No SPDIF input.

 
 

Suggestions for improvements:

1. To reduce the maximum output level at low gain by half, from 2.4 Vrms to around 1.2 Vrms.
2. Line output.
3. SPDIF input.
4. Full metal housing with clearer marking and text.

 
 

 
 
 
 

Sound quality

When I tried C5 DAC for the first time, I connected an IEM, and my first impression was, 'Wow it sounds powerful!'. Probably the main sonic character to be highlighted is the sense of good driving power, especially when driving IEMs. C5 DAC drives most headphones pretty well, but when using high impedance headphones the sense of driving power was not as strong as with lower impedance headphones and IEMs. So it is not yet a replacement for a good desktop setup for high impedance headphones, but quite a powerful DAC+Amp combo for portable setup for IEMs and easy to drive headphones.
 

 
 
The headphone amplifier of C5 DAC is quite powerful and has good dynamic and driving power. When using C5 DAC as headphone amplifier, with ifi micro iDSD as DAC, I can hear some improvements, indicating that the headphone amplifier scales well with better DAC. The following is comparison of RMAA measurement of the C5 DAC as DAC+Amp combo (White), and the headphone amplifier using ifi micro iDSD as DAC with minimum phase setting (Green). We can see that the DAC output of the C5 DAC uses a sharp low pass filter that rolls off quite early before 20 kHz. While the headphone amplifier section reaches beyond 30 kHz when using a better DAC. The 30 kHz is most probably the limitation of my HRT LineStreamer+ that I use as ADC for the RMAA measurement. A good headphone amplifier usually reaches 100 kHz easily.
 

 

 
 
Overall tonality of the C5 DAC as DAC+Amp combo, I perceived as neutral with a touch of warmness. While level of clarity is good, I do prefer a little more transparency and detail resolving power like what I hear from my AudioQuest Dragonfly 1.0c and ifi micro iDSD. Tonality is a little warm, but just a little, don't expect tube warmness here. The extra warmness makes C5 DAC pairs well with neutral to bright IEMs and headphones, for less ear fatigue over long sessions. I tested C5 DAC with 1964 Ears V3, DUNU DN-2000J, Audio-Technica ATH-MSR7/LTD, Philips SHP9500, and Beyerdynamic T1, and they pair well with C5 DAC. I like especially the pairing with Audio-Technica ATH-MSR7/LTD, and I would recommend C5 DAC for ATH-MSR7 users who are looking for portable DAC+Amp.  On the other hand I do find C5 DAC sometime could sound a little boring when driving warmer headphones such as my Shure SRH1540 and Audio-Technica ARH-R70x, where extra transparency is preferred. So my recommendation for C5 DAC is to pair it with neutral to neutral-bright tonality IEMs or headphones.
 

 
 
Stereo imaging is clear and focus, with perceived presentation that is more towards close and intimate. Not congested, but not the wide and spacious type either. For comparison, ifi micro iDSD has a more spacious and holographic imaging. As for detail and clarity, it is presented in a natural way without any emphasize or de-emphasize. Though as mentioned earlier, having used to ifi iDSD micro and other desktop DACs, I do prefer slightly higher detail resolving capability and transparency than what C5 DAC offers.
 
In summary, overall sound quality of C5 DAC is pretty good, neutral warm with very minimum noticeable coloration. The headphone amplifier sound quality seems to be a level better than the DAC section, better detail, clarity, and transparency when paired with higher quality DAC.
 
 
 
 

Features

 
 
Overall build quality is good, but not stellar. I do prefer full metal housing without any plastic parts, but it is just personal preference. The text and signs behind the transparent brown plastic cover are difficult to read in dimly lit environment. There are 2 separate USB inputs, one for data and the other one dedicated as charging port. Although it is possible to use C5 DAC while charging, but it is not recommended to play and charge at the same time.
 

C5 DAC has about the same width and thickness as the Fiio E12DIY, only slightly longer.
 
 
3 main functions of C5 DAC are:
USB DAC + headphone amplifier combo.
Standalone headphone amplifier.
USB DAC to SPDIF (coaxial) converter.
 
For easy multi-platform and driver-less operation, C5 DAC supports only PCM up to 24 bit - 96 kHz resolution. It is sufficient for me as my ears hardly distinguish any sonic improvement from files with higher resolution than 24/96, especially from a portable setup.
 
Within the 2 weeks of testing, I didn't have much chance to test USB DAC compatibility with many platforms or devices. With Windows 7 and 8 everything works fine and very stable. For mobile devices, I only tested it with a few Android devices as the following:
Samsung Galaxy S4 (SHV-E330K - Korea version) - Android 4.4.2 : Not compatible.
Samsung Galaxy S5 (SM-G901F - Singapore version) - Android 5.0.2 : Compatible.
Teclast TPad X89 - Android 4.4.4 : Compatible.
 

 

 
 
Short USB micro B to micro B cable is included in the accessories for connecting C5 DAC to Android smartphone or tablet. But in case longer USB micro B to micro B cable is required, this USB cable I bought from AliExpress has been proven to work for connecting USB DAC to tablet or smartphones:
Straight Micro Male to Micro USB B
 
 

Amplifier Gain

There are 2 level of gain on the headphone amplifier. As we can read on other reviews of C5 DAC, common feedback for the low gain is that the low gain output is way too high for most IEMs. The maximum output voltage of the low gain output is around 2.4 Vrms (2400 millivolt rms), while common IEM listening level is only in the level of up to a few hundred millivolt rms. My listening level for my DUNU hybrids for example (DN-1000, DN-2000, & DN-2000J), is only around 100 mV rms or less. Meaning, the usable volume level for IEMs and easy to drive headphones is very limited, only between 2-3 of the volume level, from the maximum level of 9. And it is a common fact that analogue volume control performs better at medium to high volume level, and best at maximum volume. In this case, for most IEMs, we can only use the volume control at low level, the area where analogue volume control doesn't perform at their best, and suffer from moderate volume imbalance between left and right channels. At low gain, the optimum maximum output is around 1.0 to 1.5 Vrms. I strongly suggest to reduce the maximum output at low gain setting by half, to around 1.2 Vrms, to have wider usable range of the volume control.
 

 
 

Amplifier Power Output & Output Impedance

The maximum output voltage measurement with 600 ohms load:
Lo gain max Vrms: 2.4 V
Hi gain max Vrms: 4.2 V
Max output current at 15 ohms load: 2.074 / 15 = 138 mA
 
Calculated maximum headphone amplifier power output at:
16 ohms: 305 mW
32 ohms: 551 mW
300 ohms: 59 mW
600 ohms: 29 mW
 
Measured output impedance of the headphone amplifier is very low, at around 0.18 ohms.
 
 

Channel Imbalance

Measured volume channel imbalance of the demo unit is between 0.15 dB to 0.53 dB, which is good. Volume level below 2 is practically too soft and not usable, so channel imbalance at volume level 1 can practically be ignored. Channel imbalance below 0.3 dB is very good, and below 1 dB can still considered good performance for analogue volume control.
 
 
 

Noise

On-Off popping noise is very soft on C5 DAC, simply ignore-able. This is for me is very important especially for portable device. Noise floor or background hiss noise if volume dependent. At low volume, below 4, hiss noise is very low and ignore-able even for sensitive IEMs. But as volume goes up, when playing silent, hiss noise is becoming louder and more audible. But even playing music at volume level 3, it is already quite loud for sensitive IEMs, so hiss noise at higher volume is practically not relevant for sensitive IEMs. While headphones are less sensitive to hiss noise, so even at higher volume, practically I didn't have any issue from background hiss noise.
 
My noise measurement for sensitive IEM is at volume level around 100 mV rms, because in average when using sensitive IEMs, my listening level is less than 100 mV. First I played a 0 dBFS 100 Hz Sine wave, and then adjust the volume and measure the headphone output until the output is measured approximately 100 mV. 33 ohms load is used as dummy load for the amplifier. Stop the Sine wave then play silent track. Observe the headphone output using digital oscilloscope, to observe the average value of the noise floor. From my observation, at 100 mV output, C5 DAC headphone output noise floor at low gain is less than 4 mV rms, which low and will be hardly audible even using sensitive IEM such as 1964 Ears V3. Starting from 6 mV rms and above, noise floor will start to be audible on sensitive IEMs.
 

 
 

Temperature

Working temperature is generally only up to the level of warm and C5 DAC never gets hot like my Centrance DACport and LH Geek Out 450. I tested once in a warm environment in Singapore, where room temperature was measured 31.5 degree Celsius, after more than an hour of continuous playing, C5 DAC case temperature only reached a maximum of 38.8 degree Celsius. In a cooler air-conditioned room, it only gets mildly warm. So, practically no heat issue with C5 DAC.
 
 

Battery

According to Cayin, battery life in USB DAC mode is around 9 hours, and around 19 hours in standalone headphone amplifier mode (AUX mode), driving 32 ohms load. I didn't measure the AUX mode, only the USB DAC mode. Continuous playback in USB DAC mode, driving full size headphone ATH-MSR7LTD (35 ohms) at low gain, volume level at 3, the battery last for 9.5 hours. Battery life performance of C5 DAC is really good. But to use the battery until it is totally empty is not recommended. And when the battery is almost flat, C5 DAC relay toggles between on and off intermittently. I suggest for the next version of C5 DAC or other models to use Schmitt trigger circuit for the relay, to avoid the relay toggles intermittently when battery is reaching its minimum operating voltage. 
Some measurement of battery charging using 2A USB charger:
Measured maximum charging current capacity: 3400 mAh (5.1 volt charging voltage)
Measured maximum charging current using 2A USB charger: 1.08 Ampere
Maximum charging time: 5 hours
 

 
 
Please take note that the maximum charging current capacity is measured on 5 volt charging voltage and not directly related to battery maximum current capacity, because the battery voltage is lower at around 3.7 volt. The right calculation should be in Watt, with some power loss on the charging circuit. Without knowing the efficiency rate of the charging circuit there is no way to accurately calculate the real battery capacity. From what I observe, the battery life is very good, and I think Cayin specification is accurate.
 
 

Bass Boost

The bass enhancement feature is pretty well done. The +6 dB bass boost area is wide, so it adds body to the midrange as well. The bass boost is not particularly boosting only some narrow area of the bass, but more like adding fullness and body to the whole tonality. The bass boost sounds quite natural and not artificial sounding like some other bass boost implementation. I guess the bass boost is done using analogue circuit rather than digital DSP, It sounds so natural that when listening to Philips SHP9500 and Beyerdynamic T1 headphones, I prefer to turn on the bass boost most of the time, to make vocal sounds fuller and bass has more body. Below is the RMAA measurement comparing bass boost off and bass boost on.
 

 
 
 
 
At this price category, I would say C5 DAC is a good performer. Not really at the level of a giant killer, but quality per price ratio is pretty good. C5 DAC is recommended for those looking for a portable USB DAC with powerful headphone amplifier to drive neutral to neutral-bright headphones.
 

 
 
 
 
 
 

Equipment used in this review:

 
 
Headphones:
Audio-Technica ATH-R70x
Audio-Technica MSR7LTD
Beyerdynamic T 1
Philips SHP9500
Shure SRH1540
 
Earphones / IEMs:
1964 Ears V3
DUNU DN-2000
DUNU DN-2000J
Jomo4
 
DACs, ADC, & Headphone Amplifiers:
AudioQuest Dragonfly 1.0c
Fiio E12DIY
HRT LineStreamer +
ifi micro iDSD
 
Computer & Player:
DIY Desktop PC: Gigabyte GA-H77-D3H-MVP motherboard, Intel i7-3770, 16 GB RAM, Windows 7 Home Premium 64 bit SP1.
foobar2000 v1.3.3
 
Measurement Instrument & Application:
Owon VDS3102 Digital Storage Oscilloscope
 
 
 

Some recordings used in this review:

There has obviously been a number of reviews of Cayin’s C5 Dac recently, due in large part to Cayin’s recent product review tour that had its genesis here on Head-Fi. I was one of those who signed up for the tour  A.) because I was curious what a portable unit from Cayin is capable of, and B.) I am actually in the market for a new portable unit and thought that the Cayin may be worth consideration. Better than paying the cost of return shipping to Amazon again!
 
For at least a year, I have been searching and researching portable units that could replace my workplace desktop rig. The idea being that I could listen to it at work, like I always do, without losing too much sound quality wise. However I can also throw it in my bag and take it home with me or  take it on business trips, airplanes, hotels, etc...
 
I have invested a fair amount of time and quite a bit money trying to find a portable solution that punches in the same weight class as my desktop rig. Up until this point I have been unsuccessful. My iFi iDSD has come the closest but still falls a bit short so why not let the Cayin C5 make its case.
 
My current desktop set up, that I am looking to replace, starts with a music library of 420 plus CDs ripped to AIFF and stored on a Glyph Studio Raid hard drive. My library is tethered to a HP Envy Laptop running JRiver 20 which busses data to a AR-T Legato USB converter feeding 1’s and 0’s to a vintage Philips DAC 960 which feeds an analog signal into an April Music Stello HP100 Mk2 headphone amp.
 
I am aware that replacing my desktop set up with a portable unit is a tall order. It is a very potent rig and plays beautifully with both my HD800 and Audeze LCD2.
 
But the audiophile tweaks eternal.
 
In a perfect world, I would like to ditch the laptop/ Glyph transport and use my iPad air instead... or maybe even a new SSD powered iPad pro eh?
Couple this transport to a portable Dac/Amp that can keep pace with and replace my Legato/ Philips/ Stello configuration and I've cut the cord... I can take my Hifi with me anywhere.
 
Because my vision hinges on an iPad transport, iOS functionality is a must.
Whether an OEM accomplishes this by shelling out cash to Apple for licensing or by using the USB Bus bypass lane of the Camera Connection Kit, I care not... I just need iOS connectivity. And the Cayin C5 Dac happily obliges via the CCK.
 
But before we get too far, just in case, a little (or maybe more) background on the company.
 
Cayin Spark states on its website that it has been in business since 1993, roughly 22 years. Personally I became aware of them only in the last 7 or so years through Stereophile and 6Moon reviews of their big brawny integrated amps. Cayin is a Chinese brand (as best I can tell), but seem to have either dedicated distribution or some division of their corporate structure parked in Germany. I could take the time to uncover what mystery here entails in the German/ Chinese connection, but it won’t affect today’s outcome. So Bygones!
 
Being a mostly Chinese brand means the audiophile community will  often view its inherent quality and brand strength with a dose of skepticism. I can attest to this personally. While I appreciate what Cayin has done and am enamored with some of their wooden clad vintage styled products, I don’t view them as a bonafide HiFi blue blood. They've put out some very blue blood quality products, but I subjectively view them as just a little 'less than' their body of work probably warrants.
 
 Cayin seems to be combating the looming specter of being “Chi-Fi” by consistently, year after year, bringing quality products to market at relatively affordable pricing (but not too affordable!) sweeping aside many of the labels, stigmas, and criticisms that follow even some long standing Chi-Fi companies. Not to mention, they have a robust US dealer network that instills confidence and have no grey market presence.
 
Cayin has placed multiple products on Stereophile’s annual Recommended Components list and have received accolades from reviewers throughout the industry. What is more (to me!) is that they are earning their accolades the old fashioned way. By making good gears.
 
They are not the ever present, schmoozing audio company who seems to always be flying a banner over this audio review site or that, always sponsoring this audio event or that. And always at the fore of audio press coverage.
 
You know the kind of company of which I speak. The darlings or insiders of the industry that always seem to be courting relationships too closely with reviewers and website administrators. They are paying sponsors at every website no matter where you turn and the audio press rewards them in kind with carte blanche coverage. Reviews, press releases, and new product announcements by industry insiders all get at least a little run with the audio press.
 
I know, I know its conspiracy theory. The truth is that these are the rules of engagement. Review sites need these paying bannermen to keep on reviewing.
But I don’t have to like it!
 
So I appreciate companies who appear committed to forging their way with product performance and design strength, and not by building out a robust marketing department and brand penetration strategies.
 
Cayin is not an insider in this regard. Case in point: I only recently found out about their, already long in the tooth, C6 amp by way of the classified section of Head-fi. People had already owned it and were rolling it out for something new and I was none the wiser. Until that point I had assumed that Cayin was devoted exclusively to large glass and gas V-8 muscle car amplifiers like the A-50T, A-88T etc... however Cayin had quietly entered the portable head-fi market and I was clueless.
 
Their most prominent piece to me, is their retro inspired SP-10a integrated amp that has been an object of desire ever since I first laid eyes on it. My only nit being its lack of a headphone jack, which I’ve always felt would have elevated it to compete with the likes of Head-Fi end game amps like the Leben CS-300 and Luxman’s SQ-38u for roughly half the price.
 
iFi/ AMR Audio have since tapped this gaping vacuum in market demand with their Stereo 50. Providing a valve based integrated with headphone capability and vintage feel without the painfully expensive cost of ownership that Leben and Luxman rigs require. Still, I would love to know what Cayin’s EL-34 based rig was capable of, were it properly fitted with a jack and a handful of resistors.
 
Alas, these big motor amps are not today’s mission!
Today’s mission is to tease out the quality, value, and functionality of Cayin’s latest portable offering, the C5-dac.
 
So Lets Dig In:
 
By the time the C-5 had reached me, it had already been globetrotting for a good month or two, making 4 or 5 stops before reaching my digs.
Upon arrival I was met with a golden/ champagne colored amp of relatively thin build and about the perfect size to ride back to back with a smartphone.
 
On top of the amp we find an original looking volume pot, analog 3.5mm line in, and 3.5mm headphone out all peaking out from behind an odd black smokey plastic cap. On the bottom there are 2 USB micro connections. One is for charging and the other is for the digital signal input. It also has a Coax digital output that is a dual mode socket that can be used with either a Coax (SPDIF) connection or a fiber optic mini Toslink. The ability to reclock incoming USB data and send it digitally via SPDIF is a major flexibility boon that allows for integration into a larger system.
 
It is a handsome little piece of kit… I like the champagne color, but like many others have mentioned here, the smokey plastic cap covering the volume pot and two jacks is an odd design choice. It looks ungainly and detracts from the products physical presence. Also worth noting is that having traveled the world and back a couple two or three times, it was a little worse for wear. The casework had a loose quality to it that I instantly recognized as pertaining to their choice of connecting the end plates with only 2 fasteners right smack in the middle of the end plates versus the usual, more fundamentally sound and rigidity inducing 4 corners.
 
So I had concerns about long terms durability from the word go, but I still want to hear how this thing sounds, so ignoring the casework demerit, I forged ahead.
 
On the side of the C5 I found the coolest thing…. A Bass boost switch.
 
I know, I know. Many audiophile puritans will scoff, roll their eyes and shake their heads with incredulity here and mumble comments of derision about signal purity but the reality is that a bass boost switch can come in handy. Depending on the headphone employed and the music being played some tone control options can add roundness, body or weight to an overly analytical, sterile or nervy tone.
 
While I get the “signal purity” argument, the truth is that amps, dacs, headphones and any of a dozen other variables imprint their signature on the signal… for better or worse. And I have fairly often stumbled across gears that strip away romance, sweetness and sunshine for the sake of high res magnification. In these instances, being able to add a dollop of honey back into the mix would be a welcome option. And unless you are a mastering engineer or recording studio professional, music is supposed to be about pleasure, enjoyment... not analysis.
It is better to have tone shaping available and never use it, than to need it and not have it.
 
Just saying.
 
So beside the bass boost switch sits another seemingly harmless switch. Though it sits nondescript and unassuming, this is not some benign little control button. This one is far more menacing and sinister than its outward appearance lets on. It is Cayin’s version of a High/Low gain switch. Or the “I’m gonna rip your driver from its surround” switch or the “I’m gonna pierce your ear drums!” switch or the “I’m going to damage your hearing” switch.
 
Kidding (sorta)... It really isn’t that bad. But in my 3 weeks of toying around with the C5 there wasn’t a single occasion where I needed the high gain setting. That is with a Sennheiser HD800, Audeze LCD2 and Fostex T50RP in hand.
 
It may come in handy with a brutally insensitive beast like the Hifiman HE6 but I don’t have one of those on hand to confirm. The high gain setting is far too loud for anything in my arsenal and I was barely able to get above 2 or 3 on the volume pot in high gain with both current hungry, low impedance planars and high impedance pro grade dynamics.
 
The silver lining here is that the C5 is a somewhat rare beast in the portable amp game that can play ball with any and all full size headphones. I have on hand an ALO Audio National and an iFi Audio iDSD Micro that can both play with certain full size headphones but both have limitations.
 
So to get the audition rolling I decided to tap my iPad air via CCK to the C5… To see how it stacks up against the field I tapped the digital line level signal from the C5 to feed my iFi iDSD micro for direct comparisons.
 
I also stacked the C5 against my ALO National, and against the Stello/ Phillips desktop set up mentioned in the opening.
 
So to answer the most pressing question, is the C5 good… Oh hell yes it is!
 
As detailed above, the C5 has its drawbacks. Especially its physical design with the black smokey plastic cap, questionable casework durability and a high gain setting that is incompatible with most headphones. But sonics here are above reproach.
 
Compared directly to the iFi iDSD the C5 plays it smoother and more relaxed. It sounds natural and free of any fatiguing extremes. If you needed a nit and were going to force a concession under duress some could argue it was too polite, but I think that’d be too stern. It is polite like a gentleman who shakes your hand warmly and looks you in the eye. Not the “I’m hiding something important from you” two faced type of polite.
 
The iDSD hits harder with big dynamics… It punches its kick drum with a sledgehammer and a few times I almost felt dizzy from the height and weight of its stereo image when a song came rushing back to full scale after a quiet interlude. Like the vertigo you get when looking up at a very high ceiling, and you feel like you lose your feet. The C5 is no slouch but still doesn’t have the same snap and pop as the iFi.
 
The C5 paints its musical picture with a pallet of warm golden highlights, autumn colors and sepia. It has ample body, rich tone and plenty of weight. The iFi is more brilliant… It paints in technicolor and splashes of neon… While it has big potent reserves for hard hitting dynamics its overall center of gravity may be a degree lighter than the C5. When it punches, it punches harder but doesn't have the same overall weight across the board... In layman terms the C5 would be "warm" and the iDSD "bright" 
 
Of the two… it was the iFi that actually induced fatigue directly out of its headphone socket first. It was too much Pixar when I wanted the real world. It can do some things brilliantly and coupling its (maybe overly enthusiastic) decoder to a warmer dance partner (like the Stello HP100) is just what it needs to bring its high flying act back down to earth. The C5 doesn’t go crazy with big acrobatic aerials. It seems to be the more even handed and practical all day all night portable unit even though it doesn't give you the same breath taking moments as the iDSD.  
 
I had not expected to like the C5 more than the iFi, so realizing we had a serious contender here, I mounted it to the DAC 960 via its coax out so it could play ball against the big rig.
 
What I found was that the C5 seems to be made of the same elemental material as the Philips/Stello combo. It presents with the same golden slant where the iFi is more silvery. Because it doesn’t have the big coils of iron or the deep capacitor reserves available that both the Dac 960 and the Stello, It doesn’t have the same gravitational pull as the big rig. It can play just as loud, and retrieves the same detail and cast the same sunshine on everything, and hit all the same notes but it doesn’t have that same ‘big motor feel’.
 
It’s the difference between going 100 MPH in a Turbo powered V4 and a fine tuned V8… You are going the same speed in both cars… Both cars can go faster so have more headroom on tap…. But the V8 has this deep power reserve that you can feel in the gas pedal and in the weight and way it carries you down the road. It has this gravitational MOMENTUM that translates into a deeper and more powerful sonic foundation. 
 
The C5 is hamstrung here by design… The iFi, National, E10, and every other portable unit I’ve ever listened to suffers the same fate when going head to head with big iron and linear class A power and tower upon tower of capacitors for deep reserves. The small boxes and their battery power limit the DEPTH at which these portable boxes can play.
 
This inordinate design difference sounds like weight… Even though the notes are the same, the tone is the same and the acoustics the same... Each note seems to spring up from a inky blackness with more gravity/ energy from the big rig and likewise the inky blackness from which the notes springs seems like its deeper, bottomless, infused with it's own energy that makes music more immersive. The depth of the stereo image deepens and players in a band play their parts with larger clearer points of separation and big black resonating spaces between them.
 
This phenomena is the main reason I default to integrated amplifiers for listening... Like the C5 can't keep pace with the Philips/ Stello deck, so also the Stello deck pales when stacked up against my collection of integrated amps at home. 
 
So the C5 won’t cut it as a desktop replacement kit for me, but there is still a lot to like here.
 
It plays music naturally and without the high res gymnastics that often leave me fatigued by up sampling high res, super magnifying gears.
 
Physically there are some issues… and hopefully Cayin will look at the issues spelled out in all these review papers and make the needed changes to casework and ditch the plastic cap. But Cayin achieves the fundamental mission of providing a very good sounding amplifier and also do the neat trick of playing welcoming partner to full size cans.
 
My HD800 simply doesn’t like portable units. Using it with my iDSD everything is too bright and it begins to grate on my nerves relatively quickly…. Likewise the ALO National seems a touch to clean (Sterile) when coupled to the HD800 and most of the substantive stuff in music that captures our emotions and takes us on a sonic journey seems to get stripped away when playing these two partners together.
 
The C5 however sounds just lovely with the HD800. It has enough refinement to hold up under the HD800 brutal resolution spotlight and plays well to the HD800’s strengths. And in that odd situation where music is compressed and dry and unwelcoming, the C5’s bass boost sonically enriches the signal allowing you to keep listening.
 
So the C5 is not perfect…. But in my circumstances it sonically kicked the proverbial ass of a piece of kit that is both highly touted and regarded in the audiophile community and twice the price. What is just as important to me, it is voiced very well to offer long term listening on the go with the HD800… An option I had thought, up until now, just wasn’t out there.
 
So between these two I think the C5 Dac sounds best out of its headphone jack. As a unit tethered to an iOS device with headphones, the C5 is a better gear. The iDSD is a more sophisticated decoder, that would be outstanding as a desktop decoder and can hold its own with dac into the $1000 mark, but as a stand alone unit connected to an iOS device using headphones. I think it gets fatiguing on a listener relatively quickly.
 
So If you are just geeking high-res as a consumer and care as much about format, bit depth and bit rate as you do which artist and what album, then the C5 still works, but may not be the strongest choice.
 
However if you are looking to connect flagships like the LCD2, HD800 or T1 to a portable and love listening to music, the C5 earns my highest recommendation. Sweep aside internal conflicts about its low price, and Chinese origin and quality... If it is music you crave, this one will give it to you proper.
Consider that it is priced just north of $200 a gift… a gift that you can take to the record store and buy more music with.
 
Peace Out!
 
PS UPDATE: I PUT MY MONEY WHERE MY MOUTH IS AND BOUGHT A C5 DAC.

 
I first joined Head-Fi in November of 2014. At the time I owned a couple of pairs of IEM’s, and had just purchased my first DAP (Fiio X3) and over ear headphones (Sennheiser HD598). I really liked the X3 with my IEMs, but found something missing with the HD598s, especially in the bass and body. I started researching portable headphone amps – even starting a thread asking for suggestions – and had several names put forward, which through further research I whittled down to the Fiio E12A and Cayin C5.
 
Not having any place in Calgary to try out either amp, I chose the E12A based partly on its suitability for IEMs and full-sized cans, and partly on aesthetics (I found the C5 looked a little “off” with the clear plastic end cap). While I was very happy with the E12A, I remained curious about the C5, and was impressed with the ongoing positive feedback the product received in discussion threads.
 

 
Fast forward a half-year, and I got the opportunity to demo the C5 at the Calgary Head-Fi meet, courtesy of Jeremy (@EmpJ) at CTC Audio. I was very impressed with the sound quality, especially with hard-driving cans like the ATH-R70x and the K7XX, and came close to purchasing one, but already had 4 other headphone amps and decided to hold off. Fast forward another couple of months, and I got the opportunity to try the “Son of C5” in the form of the C5DAC “Spark”, courtesy of a Cayin-sponsored product tour. And that brings us to the present, and this review.
 
Disclaimer: I am not affiliated with Cayin, and have not benefitted from this review opportunity (other than having the opportunity to try out an excellent piece of equipment). I was provided with the C5DAC for a limited time in exchange for my unbiased opinions.
 
About Me
 
Before getting into the review, a little about me. I’m 50 years old, and so probably have deficiencies in my hearing (in a recent, entirely non-scientific test I discovered I can’t really hear anything over about 15 kHz, with roll-of starting around 12 or 13 kHz, which is pretty good, I guess, for someone of my vintage). I’ve been a music lover for decades, but am still relatively new to the MidFi/HiFi/Head-Fi game; I haven’t listened to a lot of high-end equipment (yet), and am not an expert on the technical aspects of electronics or musical terminology. I have read a lot of reviews and threads on Head-Fi, and spend a lot of time on the site; as such I know what has been helpful to me in reviews and endeavor to provide what I consider useful insights to help others make decisions about items they are thinking about trying or buying.
 

 
I listen to a variety of music genres, in particular, Classical (mostly mid 1700s to mid/late 1800s), Jazz (‘50s to 70’s), Rock and some Prog-Rock (‘70s), ‘80s New Wave/Electro, and Trip Hop/Acid Jazz (90’s into 00’s). My preferred sound signature would be characterized by a good sub-bass presence, tight mid bass, and relatively linear, detailed mids and highs. I like my music quite lush and rich, but with a good level of detail. I’m not a bass-head, am not a big fan of anything too boomy, and don’t like highs that are too intense or harsh.
 
The Review: Design and Build Quality
 
So, without further ado, let’s dive into my impressions. The C5DAC shares the look and feel of the C5 Portable Headphone Amplifier; in fact, the two are identical in almost every way, except for the back plates (colour and plug configurations) and lettering inside the plastic front cover. The main casing of both pieces of equipment is an elegant, champagne-coloured, satin-finished metal (they now also come in black… pretty Stealthy), with plastic end pieces on the front and back with various plug-ins and switches. The metal casing envelopes top and bottom, and wraps around the sides, with a gap running down the left and right sealed in a dark, opaque plastic. The unit is surprisingly light (I measured it at 181 grams); I expected it to be heavier when I first looked at it.
 

 
Looking at the six sides of the C5DAC we have:

1. Top: Clean finish in champagne gold, with 3-light battery charge indicator on the back end, and the cursive word “Cayin” imprinted near the front.
2. Bottom: Similar to the top, without the battery indicator. Item information is included, and access to the reset button is situated near the back end piece. The C5DAC comes with four silicon buttons attached; these can be used as feet, or for resting a larger DAP to avoid direct contact and scratches when stacking (Fiio X5ii and Hidizs AP100 fit very well, but Fiio X3ii was too small to stack using the feet).
3. Left side: Small, triangular plastic Bass Boost and Gain switches. These jut out very slightly, are easy to manipulate and seem quite sturdy; however they appear a bit cheap and detract from an otherwise quite solid design.
4. Right side: Nothing, just the plastic bar running from front to back separating the top and bottom metal sheets.
5. Front: Uniquely shaped end piece with recessed volume control, all covered with a semi-opaque brown plastic cap. On the left part of the cap there are two plug-in points for Line In and Headphone Out (HO), and on the right there are openings on top and bottom access to the volume pot (which has ridges for easy grip). Power is controlled by the volume pot, which clicks solidly between the on and off positions. When on, a small orange light turns on next to the volume pot. The volume pot is relatively stiff, but turns smoothly; being mostly covered by the end cap, it is well protected from inadvertent turning when in a pocket or bag.
6. Back: Here is the other business end of the unit, in black plastic (this differentiates the C5DAC from the C5 as the C5 end piece is champagne-coloured plastic).  Looking at the back end directly, from left to right we have Coax Out (for connecting to an external amp), micro USB port for DAC input from phone/laptop or charging an external device, a small switch for controlling the USB DAC/charging function, and another micro USB port for charging the C5DAC.

 

 
Overall I like the look of the C5DAC, but I’m not a big fan of the plastic front end-cap, or of the bass boost and gain switches. Personally I think the end cap is a bit ugly, and it seems flimsy; I was able to pop it off quite easily (though I’d prefer to keep it on as without it the end is even uglier), and I can imagine it cracking or breaking if the unit is dropped on a hard surface. As mentioned already, the bass and gain switches appear cheap and detract from an otherwise quite solid design.
 

 
Out of the box, the C5DAC comes with almost all the cables and accessories required for pretty much any set-up. There’s a grey cloth drawstring protective bag (protection from scratches, but not so much from dings or drops) and two bright blue stacking bands (why blue I’m not sure, but they certainly are distinctive). Cables include:

1. USB to micro USB cable (for charging, and for hooking up to a laptop)
2. Short micro USB to micro USB OTG cable (for hooking up and Android phone)
3. Short 3.5mm to RCA Coax adaptor
4. Short 3.5mm to 3.5mm interconnect cable

 
The only thing missing for my usage preferences is the Lightning Camera Connection Kit (CCK) cable, but I know Apple is finicky about patents and who can do what with what, so this is not a huge issue. It would be nice if the protective bag was more case-like and sturdy, but it’s not such a concern that it would deter me from adding the C5DAC to my collection. And the blue bands… I’d prefer something that matches better (brown or grey), but this is not a deal breaker either.
 
The Review: Listening Impressions
 
And now we get to the meat and potatoes of the review. As mentioned, there are things I like and things I’m not so fond of with the design of the Spark, so this bit is ultra-important. If the sound blows me away, I’ll forgive any aesthetic or design issues.
 

 
As a relative neophyte in the reviewing game, I’m still not the greatest at describing what I hear in absolute terms. I’m still learning about humps, peaks and dips in frequency response and what exactly qualifies as sub- and mid-bass or lower- and upper-mids. What I am able to do more confidently is compare what I hear from two different sources, so that’s where I’ve focused my observations.
 

1. Macbook Air with and without C5DAC: I don’t listen to my MacBook through headphones very much, and when I do it’s usually via a desktop set-up, so this test was interesting for me.  Benefits of an external DAC were clearly illustrated by the Spark. I listened to a number of tracks here, and I’d say my MacBook on it’s lonesome was at various times hollow, one-dimensional, syrupy, lacking texture and impact, polite, bleedy and lacking atmospherics. Adding the C5DAC transformed the quality of output, with sparkle, transients, twang, clarity, warmth, emotion, and expanded soundstage. I don’t think I’ll listen to music straight out of my laptop ever again!

 

1. iPhone 5S with and without C5DAC: I only use my iPhone for music when I head out for a run, at which point “audiophile” is not my main concern. This comparison and analysis of the iPhone’s sound capabilities was thus also an interesting one for me. Hooking up this combination was a bit of a nightmare ergonomics-wise as the lightning CCK and USB interconnect was unwieldy and inelegant. If you’re looking for a pocketable (big pocket) stack, this is not it. If you’re thinking of switching phones (iPhone to Android or vice-versa), this is definitely a point in Android’s favour. That said, I found the Spark benefitted sound quality in similar fashion to what it did with my MacBook, with improved detail and dynamics, and expanded soundstage. If I’m ever forced to give up my DAPs, I’ll definitely be looking to a C5DAC (or other portable DAC) to keep my musical enjoyment levels up.

 

1. C5DAC vs. C5: Both pieces have a very similar sound presentation, which I’ve described already as warm, dynamic and detailed, with excellent soundstage. In general listening I found little to distinguish between the two. When A/B testing, I found subtle differences, with the C5 marginally more detailed and clear and C5DAC smoother. The C5 is also very slightly more powerful than the C5DAC, though both have power to burn and drive the 470 Ohm ATH-R70x easily with room to spare. Hard to say which I prefer, so it comes down to whether or not you need a portable DAC in your rig; if your music source is a phone, I’d choose the Spark, and if a DAP, the straight C5 Amp. YMMV.

 

1. C5DAC vs. E17K (as DAC): On Low Gain, E17K is more clear and dry up high with good micro-detail, but a touch lacking in bass, life and joy. Female vocal is thin. Soundstage has breadth, but lacks depth. C5DAC is its usual warm self, with thump, punch and energy. Female vocal has soul, rising up from the depths of the chest. Soundstage closer in, but with depth and an enveloping, cozy feel. Switching the E17K to High Gain resulted in better balance than in Low, with more punch to the low end and roundness to mids and highs, though less alive and inviting than C5DAC overall.

 

1. C5DAC vs. Soundblaster E5 (as Amp): I could have compared these two on the DAC side of things, but wanted to play with the Spark as amp only, hence this set-up. In comparison to the E5, the Spark has punch and dynamics down low and oodles of detail in mids and highs. Soundstage here is club like, with welcoming, cozy room feel. E5 also sounds very good, though the feeling is more of a studio setting, with sound absorbed by walls rather than bounced back to the listener. Overall sound is drier, less gut-busting in the bass and smoother in the mids and highs. I liked both amps in this pairing, and would go with the E5 for a long, fatigue-free listening session, and Spark for a single-album, detail focused sit-down.

 
In my listening I found that the Spark’s warmth matches very well with dry, more analytical headphones. I really enjoyed the combination of C5DAC with the ATH-MSR7, and with the AKG K7XX. The Spark added richness and life, especially in the low end and mids, while the MSR7 and K7XX really showed off the C5DAC’s potential in the treble.
 

 
If I were to pick out the main qualities of the C5DAC, I’d say it’s warm (welcoming, enveloping), dynamic (energetic, strong sense of mood, with balance across frequencies from low to high end), detailed (nice texture, good instrumental definition), and powerful (drives even power-hungry, full sized cans), with excellent soundstage (wonderful sense of air and space, and precise positioning).
 
 
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Conclusions
 

 
If it isn’t clear by now, I really like the Spark. If you’ve tried the C5 amp and fallen in love with the warm, detailed, dynamic and welcoming Cayin “house sound,” you’ll be equally enamoured with its DAC-wielding offspring. While I have minor issues with some of the aesthetic choices taken by Cayin (Johnny Ive look away now) and would prefer more play in volume control for IEMs and less cable clutter with iDevices, I find the sound signature addictive and love Spark’s versatility. I definitely give the Cayin C5DAC two thumbs up!