I'm sorry to anyone who had been looking forward to my thoughts about this unique DAP, but I became involved in other things and time just flew by ...
I've had a chance now to use my C4 Pro (firmware version 1.00.02.01 downloadable from http://www.colorfly.eu/download.html) for a few months, and I believe I now have a good understanding of its capabilities, its faults, and other small details, specifically when used with a Mac.
Pro - Design
Beautiful aesthetics for anyone who likes retro designs. I've been an audiophile—and earned my livelihood in the specialty A/V industry—for 26 years, so for me the VU meter, the sliding potentiometer, the solid walnut case and its woodcut engraving, and the metal face with the aged bronzed look all appeal to my sensibilities.
Con - Design
The metal parts are easy to scratch, although not being highly noticeable scratches unless the unit is gouged—instead, tiny scratches. An example is when I first started using the C4 I was constantly plugging in and out the included mini USB cable (more about this later) and I later realized that my trying to fit the connector into the C4 had been a bit sloppy since there were now tiny scratches around the mini USB jack. Again, nothing highly noticeable, but with the right light and the right angle, noticeable. Given the aged appearance the finish applies to the metal surface, this isn't as bad as it would be if the surface had a more uniform consistency.
Pro - UI
The menu is simple enough to navigate with the arrow controls, menu button, and the centrally placed power button. The navigation will not remind anyone of an Apple device since there are areas that can seem counter intuitive at first, but once there is familiarity with the controls everything seems easy to get to (I'll comment more on the controls in the con section). The display is of a type that provides good resolution—at least to my aging eyes—of the small font used and there are indicators in the topmost area for repeat mode, track number/number of tracks of the folder being played, sample rate converter setting, digital input/output setting, EQ setting, and the battery level. Just beneath is the track playing info if the file has ID tags and it does scroll on a continual basis. Below this is the aforementioned VU meter—mono—which probably has more aesthetic value than functional value. Below the VU on the left side is a play/pause indicator and below that is the elapsed time/total time of the track being played; to the right of this is the bit rate and the sample frequency displayed with a larger font. The bit rate and sample frequency info either denotes the native rate of the file or any of the SRC rates chosen. Finally, below this information is a scrolling display of the file name, especially useful if you like to strip away any ID tag info.
The menu button sits in the upper left corner on the main surface of the C4, and this along with the power button provides access to settings for repeat mode/shuffle, display brightness and duration (5-30 seconds or always on), language (Chinese, English, German, Italian, Portuguese, Dutch, French, Spanish, Polish, Russian, Turkish, Danish, Swedish, Japanese, and a few others I didn't recognize due to the labeling being in the native language), audio output settings which include sample rate, digital filter (fast or slow), absolute phase (nice!), and whether the digital output is on or off. The remaining options are digital input settings (play mode, SPDIF input, SRC only operation) and system info which displays among other superfluous info the firmware version and the storage capacity/usage of the internal/external flash memory.
Besides the volume slider which by the way typically keeps its place when the C4 is pocketed or placed in its included leather sleeve, there is a plastic toggle button for the SRC setting which cycles through native, 24/88.2, 24/96, 24/176.4, and 24/192 settings. Pushing the toggle in the opposite direction sets the EQ settings (normal, rock, pop, classic, bass, and jazz). I find the EQ settings unusable.
The front end of the C4 has headphone outputs for 1/4" and 1/8" headphones (purportedly good for up to 300 ohm headphones), a micro SD card slot with no cover (the manual claims up to 32GB compatibility, but I've read that a 64GB card can be used as long as it is formatted as a FAT32 directory and a card reader is used when transferring files—haven't tried this yet), a coax digital input and output, a tiny hole where the reset button resides, and the mini USB jack. Since I use my C4 as a source component for my main system, I can't comment on the battery life.
Con - UI
Most of the control buttons take a bit of getting used to. Again, this is no Apple device since instead of just giving a button a quick push, one has to camp down on the button for a second or two for there to be any response. Sometimes even this will not produce the desired result and one will find themselves letting go of the button and pushing it down again until the action is achieved (I find this analogous to how my brain works as I get older and older
. The arrow control and menu buttons of the C4 are of a membrane type, and based on my previous experience with such buttons, the plastic used for the membrane may be susceptible to indentations or even cracking as it ages—only time will tell if this indeed becomes an aesthetic issue.
The volume slider is a bit loose and wiggly; I expected that since the C4 was advertised with an Alps professional pot, it would feel as solid and ultra smooth as other high quality slider controls I've used over the years. Alas, it does not, yet the sliding action does feel good. Incidentally, I've read that this pot is resistant to becoming noisy as it ages since there is some method it employs which keeps the slider protected from any debris.
The VU meter acts strangely when playing back FLAC files. On my unit there is a sluggishness and jerkiness to its action. With WAV files, the VU works as expected—highly responsive.
There are a couple typos ("Interal Flash") in the menus as well as other little oddities in its functionality, but they aren't deal breakers.
Pro - Sound
Now to the good part—this is a fantastic sounding player. I've never auditioned the Astell & Kern AK100/AK120 players or the comparable iBasso and HiFiMAN players, so I can't comment on how the C4 compares; I can only say that when hooked up to a commensurate set of headphones or to a really good music system (see my profile for my current main system if interested in learning what I use the C4 with), the C4 reveals itself as a high resolution source component. Of course, this is predicated upon using lossless files—especially 24/48 or higher—this is not a device for lossy MP3 files unless casual listening is one's habit.
As previously mentioned, I do not use my C4 as an on-the-go player; I instead use it as a source component for my main system. I wanted to have an inexpensive component that would play the ever growing library of downloadable high resolution files that have become available over the last several years. I began purchasing music from the HDtracks website as well as downloading the Bowers and Wilkens Society of Sound files that I received for free for purchasing a pair of B&W headphones, and although I could always hook up my MacBook Air to my system, I found this to be a cumbersome solution. I have a Wadia 831 CD player that I have compared the C4 to and I find the C4 a commendable alternative—and a better source with
some of the 24/96 files I have purchased (not all high resolution music files sound better than my Wadia, at least to my ears, and certainly not better than many of my well made and recorded vinyl records although this may be due to limitations in the C4's componentry).
The sample rate converter does give the sound of some of my files a noticeable difference in low-level detail, soundstage width and depth, and overall air. I generally use the 24/192 setting with my 24/48 and 24/96 files, but as you will read in the con portion of this section, there is a sonic cost, one that gives me pause in recommending this feature of the C4.
The tonal quality of the C4 is fairly neutral. I abhor a top end that is elevated in any component since the beryllium tweeters on my Focals can be quite revealing of any discontinuities. The trebles from the C4 are extended yet smoothly reproduced. The midrange is neither forward or recessed; vocals float within the soundstage with a good sense of air surrounding them. The bass does come across light sounding, without the wallop and extension of my Wadia. I attribute some of this to the power supply limitations inherent in a portable device and wonder whether a dedicated power supply would enhance the bass impact—probably so. Still, without doing direct comparisons to my Wadia (or in some cases to my Clearaudio turntable), the bass reproduction of the C4 is satisfying in most regards.
It should be mentioned that the sound is noticeably better when using the 1/4" headphone output. I believe this may be due to the quality of the connector compared to the 1/8" jack. It may also be due to any circuitry difference between the two jacks.
Con - Sound
Although abbreviated, I've already written about the frequency range, so in this section I will focus instead on some of the audio anomalies of the C4.
The use of the sample rate converter poses a problem ... and this could be a deal killer for some. There is a popping noise that occurs between tracks when the SRC is engaged. This is most disturbing when listening to live recordings or classical music since most of these recordings do not have any gaps between tracks, yet the C4's SRC circuit still makes this annoying popping sound. If the SRC is disengaged, no popping sound, but then one loses any sonic benefit of oversampling. Still, I have opted to leave the SRC disengaged, but I find this to be a frustrating solution since the SRC is an integral feature of the C4.
Prior to writing this review, I visited the European Colorfly website just to check on whether there had been a firmware update. I recalled there were comments on the website that stated the version installed on my C4 (1.00.02.00) had addressed the popping noise—
in some cases. I was happy to see that a new version had been released (1.00.02.01) although there weren't any comments on what changes had been made. Hoping the popping noise (or gapless playback which I'll get to momentarily) was addressed, I updated my firmware but there didn't seem to be any difference. So, I'm not sure what the new firmware was supposed to do (I freely admit this new version may not be new and was posted all along—I just didn't notice it before given the way it is listed).
I have a few live recordings as well as many classical recordings on my C4. Not having gapless playback is another annoyance. When listening to these types of recordings—in most instances—there is a momentary muting of the sound between tracks. It only lasts for a second, but this muting takes away from the listening experience. I can't believe that a DAP in this age of technical advancements would forgo this essential capability. I certainly hope there will be a firmware update that resolves this problem as well as the popping noise.
I need to add that I've never used my C4 as a DAC only, so I cannot comment on whether the problems I've described happen when the C4 is used in this manner. Additionally, I don't have MP3s on my C4, so again, no comment.
Another limitation of the C4 is that it will not play back 24 bit FLAC files, only 16 bit. As a result, the files I have downloaded from B&W and HDtracks (24/48 and 24/96 FLAC) have to be converted to WAV files at the expense of limiting how many songs I can load onto my C4. Yes, I can always buy more SD cards, even 64GB cards, but I'd rather not have to do so. Again, I hope this is addressed in the future but this has been a well known long standing limitation.
(For the technically savvy, does the conversion of my FLAC files to WAV lead to any data loss? I assume not, but I'm not clear on this and would appreciate any comments.)
Pro - Incidentals
I have to repeat how beautiful the C4 is and how good it feels in one's hand. The weight, to me, is just right, not too heavy and not too light. The construction and attention to detail is very good and the cardboard box it comes in exudes something special is inside. The black leather slipcase is a nice accessory; I initially felt from the website pictures that the case was a bit too garish with its red stitching, but after seeing it in person and especially as the leather has broken in with use, I like it very much. It holds the C4 firmly and will protect it from any unfortunate event. The included USB cable is about a meter long, has an embedded RFI filter on one end, and its outer jacket has a nice textured feel to it. The connectors are gold-plated; as to whether that really makes any tangible difference for a power/transfer cable, who knows, but its nice anyways.
Con - Incidentals
The power supply included was of no use since it had a European plug. I have an extra Apple USB wall plug that I use to power my C4.
As mentioned, I have a 2012 MacBook Air. Transferring files over to the internal flash storage is an exercise in frustration since at times the C4 quits and freezes up. One then has to unplug and reboot—sometimes do a reset—and try again ...
from the very beginning. Imagine you have 32GB of music 80% done and then the C4 freezes up; highly frustrating, especially since whatever internal flash memory is used must be a low speed class—it takes a very long time to transfer files. I've had this happen to me several times at different time intervals. I've read others who have reported this problem, so I don't think it is a compatibility issue or something to do with the USB cable and its connection (I've tried a different cable and had the same experience).
Macs leave hidden folders/files on the C4 after an eject. The problem with this is the C4 shows these hidden folders/files in its directory, taking away from easily navigating the nested submenus. I did find a solution to this with a tiny app called Eject for Windows; you can download it here:
http://www011.upp.so-net.ne.jp/decafish/EjectForWindows/EjectForWindowsE.html
This app works great in removing this litter on eject. Oh, one other thing, there is no sorting after a transfer, so for those of you who like to keep things in alphabetical order (as I do), you'll have to transfer your files in the order you want since the C4 uses the date stamp to sort any files. This does make adding any new files to the internal flash a problem; using a reader with a higher speed SD card is much easier to work with since files transfer much faster.
Finally, I question whether I will ever have any problems regarding service due to the non-existent distribution in the U.S. eBay is the only way to purchase a C4 from what I've experienced, and the Chinese vendor I bought my unit from was not exactly the easiest to communicate with. I presume I will be able to use the European distributor for any service, but I'm not sure. I was able to download firmware from their site using my serial number, and I did have an email exchange with the distributor about some of the glitches mentioned, but given the low profile of Colorfly, who knows how long their product will be supported. It's really a shame since the C4 deserves greater attention.
I think I've written enough. If anything else comes to mind, I'll continue this thread. I hope some of you found this review helpful in deciding on whether or not to purchase a Colorfly C4 Pro. For the most part, I'm happy with my purchase ...
The folders were there but no files ? 
