Steven Stone is the former editor of AudiophileReview.com. He a longtime audiophile and home theater writer, as well as a musician and recording engineer. Steven has written for publications like Stereophile, as well as HomeTheaterReview.com, AudiophileReview.com, and The Absolute Sound.
Steven is plays guitar, mandolin, and Ashbory bass and is a collector of fine musical instruments.
The Colorfly C4 portable music player causes polarized reactions - prospective owners will either fall in love or hate it almost immediately. In over 30 years of reviewing all sorts of audio devices from phono carts to DACs to power amplifiers and speakers, I've rarely come across a device that I so wanted to like that left me so consistently stymied by primitive ergonomics.
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Priced at $799, the Colorfly C4 is positioned to compete with the Astell & Kern AK100. For only $100 more than the AK100, the Colorfly offers several key features, including the ability to function as a sample-rate converter and SPDIF DAC. According to Colorfly's site, the C4 is the first portable player to support 192/24 files, as well as the first with under five picoseconds of jitter and the ability to drive 300-ohm resistance earphones.
Unboxing the Colorfly C4 will provide prospective owners with their first surprise: it's much larger than most portable players. The C4 is slightly longer than an iPhone 5 at 0.75 inches wider and twice as deep. The top surface is finished in what can best be described as an antique brass finish. It reminds me of an old Emerson humidifier I used to own. The back and sides of the C4 are made of "black walnut from North America." On the back is an intricate hand-carved logo featuring two library lions on either side of a shield with a big C on it. I guess that's Colorfly's coat of arms. Impressive. The C4 comes with 32 gigabytes of internal memory, as well as a slot for a microSD card. The largest card currently supported is 32 GB.
The C4's ergonomics are as unique as its looks. You won't find a touchscreen or even a regular keypad setup. Instead, Colorfly decided to reinvent the control surface. The top third of the C4 has a color display; however, instead of a touch-sensitive control face, the C4 has a large ALPS professional volume slider on the right hand side and two overlapping squares with six pushable function buttons on the left. Below the upper square is a two-button switch for changing the preprogrammed EQ and the sample-rate converter settings. At the center of the two overlapping squares is a square red button that functions as on/off, play/pause, and select. All of the C4's inputs and outputs are located on the bottom edge of the player. There you will find a micro-USB connector, an RCA SPDIF input, an RCA SPDIF output, a microSD slot, and two stereo headphone jacks.
All charging and transferring of files to either the internal memory or microSD card is supposed to happen through the USB connection. I found that the charging functions worked correctly, but transferring files via USB was less successful. After several minutes of copying files, the operation would cease, and an error message about an incorrectly removed USB device would pop up on my Mac's desktop. Some files were copied successfully, but not all. After multiple tries, I resorted to adding files to a microSD card via a USB card reader and then using microSD cards as my primary music file source with the C4. The C4 preferred files to be in folders rather than just residing at the root level. Any music files that were not in folders were not recognized.
Once you have some music in the C4, the rest is relatively straightforward ... almost. One quirk I found was that, if I tried to change settings while music was playing, it was impossible to back out of the nested menus. No amount of pushing the "back" button made any difference. Once the music was paused or stopped, the back button functioned properly. Another ergonomic quirk was that, while the C4 will play higher-resolution FLACs, it can only play them if they are 16-bit depth; 24-bit FLAC files, such as the Beatles collection released on USB a couple of years ago, won't play on the C4 unless converted into WAV. According to Colorfly, the C4 supports FLAC 16-bit up to 192 kHz, WAV 24-bit up to 192 kHz, APE, MP3-320, and Ogg Vorbis file formats.
Best audio practices dictate that you should always turn down the volume on any device when you turn it on or off. This is especially true for the C4. If you fail to turn down the volume, you will hear a thump when you turn the C4 off and once again when you turn it on. If you were listening at a high volume, the thump will also be loud. While the C4 is certainly not the only device that makes a turn-on/off noise (the Mytek 192DSD DAC also has a turn-on/turn-off thump), it's one of the few that doesn't mention the issue or suggest a "best practices" solution.
The C4 has two headphone connections: one is for standard 0.25-inch (6.3mm) stereo jacks, and the other is for stereo (3.5mm) mini-jacks. On the Colorfly site, you can find fairly comprehensive tests of the C4 for 16-, 32-, 100-, and 300-ohm impedance devices. With a 32-ohm load from the 3.5 jack, the C4 puts out a maximum level of 618 mV. With a 300-ohm load in the 6.3 jack, the C4 puts out a whopping 1,988 mV of output.
Unlike the power source in some players, such as the HiFiMan 601, the C4's battery is not replaceable. It's hardwired into place. If long battery life is important to you, you'll be disappointed to learn that the C4 won't keep going and going. I got slightly over 3.5 hours from a full charge at first. After a few cycles, battery life improved somewhat but, if you are planning a long trip, I suggest getting a couple of USB battery/power sources to supplement your power options so that you don't end up having to pretend you're still listening to music at the five-hour point in your trip.
Read more about the Colorfly C4's performance on Page 2.
One final oddity I must bring to your attention: Colorfly is very proud of the 3U gold-plated RCA SPDIF digital input and output on the C4, and I would expect they would prefer that you use cabling of equal quality. That's difficult to accomplish, because the space between the outside barrel of the C4's RCA jacks and the edge of the antique brass case is so small that many high-end RCA cable outer barrels are too thick to fit into the limited space around the C4's RCA connections. I had to go through most of my cable collection before I found an RCA cable that would work. Fortunately a 10-year-old Audioquest cable had removable barrel hardware. With the outer protective barrel removed, the cable fit ... barely.
When connected as an SPDIF DAC, the C4's upsampling feature is pretty neat. You can upsample any digital stream that enters via the RCA digital input. You can select a sampling rate of 88.2, 96, 172, or 192. You can also use the C4 as strictly a sample-rate converter by running its digital output into another DAC. I was somewhat surprised that the C4 didn't offer the ability to function as a USB converter, so that you could use it as a bridge between your computer's audio and the rest of your system. This would have greatly extended the C4's applicability for use as a "bridge device."
Before I discuss how the C4 sounds, let me explain why it sounds
as good as it does. The heart of the C4 is the CIRRUS Logic CS4398 chipset. Combined with the CIRRUS AD823 chip, the CS8433 SRC chip and the TCXO crystal oscillators, the C4 delivers up to 120dB signal-to-noise and less than five picoseconds of jitter. Although the CIRRUS chip has the potential for 120 dB S/N, the actual published specification for the C4 is 108 dB with total harmonic distortion of less than 0.003 percent. I quickly discovered that the 6.3-diameter headphone output is the alpha dog of the two. Early adopters on the Head-Fi site also found that the 6.3 output jack delivered consistently better dynamic contrast and "drive" than the 3.5 mini-stereo jack. Even if your headphones are made with the smaller diameter connector, I would recommend using an adapter so that you can take full advantage of the 6.3 jack's output capabilities.
Sonically, the C4 is certainly on par with the best portable players I've heard. On standard 44.1/16 and 320 MP3 files, the differences between the C4 and the two Astell & Kern players, the AK100 and AK120, were essentially nonexistent. Instead of relying on my aural memory, I set up a nice robust A/B test that you too can do at home. All you need is a multi-output digital converter box and the necessary cables and adapters. What I did was take the USB output from my MacPro desktop unit and run it into the Trends UD-10 DAC and converter, which gave me an RCA SPDIF feed for the C4 and Toslink feed for the AK120. The headphone outputs of both players were then routed to a nifty little $25 A/B/C/D box, the HS2, created by FIO for comparing different portable player's headphone outputs. Once I matched the levels between the C4 and the AK120, I was unable to discern any differences using commercial recordings. All those folks on Head-Fi who claim that the C4 lacks a bit of low-bass boom when compared with the Astell & Kern players should try to do a similar matched-level, instant-switching A/B test. I suspect that the harmonic balance differences they are hearing are more the result of small differences in volume level rather than fundamental harmonic differences between players. Using the FIO HS2 comparator box and a wide variety of headphones (including the Audeze LCd-3, AKG K-701, and even Stax 407 earspeakers), I simply could not tell which player was which. Perhaps the FIO box is not of "sufficiently high resolution" to pass minute differences, but harmonic balance differences should come through, even if the resolution is compromised slightly by the FIO.
As advertised, the C4 had no trouble driving even my Beyer Dynamic 600-ohm DT-990 headphones well past my maximum-volume comfort level. With lower-impedance cans, such as the Audio Technica ATh-900X, the C4 volume control rarely got more than halfway up. I especially liked how well the C4 sounded when driving my Grado RS-1 headphones. The Grado's bass response had the kind of punch I'm used to hearing from a decent outboard headphone amplifier like the Bryston BHA-1 headphone amp.
To compare the external SPDIF input with an internal music file, I used a live 96/24 recording I made of Chris Thile on mandolin, Chris Eldridge on guitar and Gabe Witchter on violin, playing outdoors, complete with occasional low-frequency wind noises. Unfortunately, the switchover wasn't as fast as I would have liked. To go from the SPDIF input to an internal source, I had to physically disconnect the RCA digital cable before the C4's controls would accept the keyboard command to switch back to playing from its internal memory. Despite the lag, it was clear that, regardless of whether it was playing a file from its internal memory or an external SPDIF digital source, the C4 did a wonderful job of handling the big bass wind transients, while preserving the delicacy of tone from three beautifully-played acoustic instruments.
Competition and Comparison
The main competition for the C4 comes from two other companies that also specialize in portable audio. Astell & Kern has two portable players that anyone considering a high-definition-capable portable player should also investigate. The AK-100 ($699) and the AK-120 ($1,299) both offer slicker ergonomics and greater external memory capabilities, coupled with equally splendiferous sound. HifiMan has the HM-801 ($749), which only delivers a maximum sampling rate of 96k, but has a rock-solid interface.
By coupling fabulous sonics with what could only be described as an idiosyncratic interface and control surface, Colorfly has created a component destined to attain cult status. If you don't mind the ergonomic obstacles, such as difficulties with importing music into its internal memory or the need to disconnect the digital SPDIF cable before you can change back to playing internal music files, the sound quality and high-definition capabilities of the Colorfly C4 may win you over.