Getting this thread a little bit back on topic. Even today I am convinced the Colorfully C4 is a very relevant music player. I already owned the C3 for a couple of years and was very much impressed by the sound and build quality, using a serious DAC and amplifier part. After saving up some money I decided to step up to the C4 for a couple of reasons. First of all that the player is developed with one major focus: get hifi quality in a portable device. Where most other DAP's have multiple focus (UI, Design, Batterylife, Weight, Portability and Sound for example), the team that builded up the C4 had only one goal: sound as good as possible. I'm sure that approach is still very relevant today. Another reason is the combination of an excellent chipset with a unique technique to kill jitter and some serious op-amps. I know the quality of the Cirrus CS4398 because of the Marantz CD6005, which is my present player. It has a fabulous soundstage and a ultra high level of detail and I was thrilled to hear that such a high-end chipset was in the heart of this DAP. And, to under scribe this, the chipset is still very relevant today, used in the latest Marantz CD models. another function which is a real pro in comparison with other modern DAP's is the possibility to upgrade the sample rate of a song. And yes, you can hear the difference definitely. The sample rate converter (also a high standard component of Cirrus) makes it possible to upgrade native CD 44,1/16 WAV up to 192/24, taking away the typical cold analytic and harsh CD sound, turning it into a neutral analogue sound. Very relevant when you mention the revival of analogue sources as vinyl.
Finally I got my C4 about 3 weeks ago. I don't care so much for a burning-in schedule, I think the win you make is less then 1%. 99% had to come form how it sounds the very first time starting it up. And I can be short about that: It is HiFi, every second, every note, every song. Period. It makes completely no difference in sound if I have my AKG K550 headphones connected to my Marantz cd65005 /pm6005 cd-amp combination or in the C4 (without using the sample rate converter). The soundstage is tremendously in front and wide, details are incredible fast and correctly placed in the picture. The balance is perfect and with the src on 192/24 I even found myself more enjoying music for hours without one moment of irritation or exhaustion than my actual cd-amp combination. Really, my ears experienced a overwhelming neutral but slightly warm (guess it is because of the src's capability of taking away the cold and harsh cd-sound) sound that never got boring. I tested only 44,1/16 (with src on uprated to 192/24) and the quality was just amazing. All the records I tried are well known by me (ripped them for my own collection), but gave me the extra of uprated spacious warm HiFi. I especially liked records with a high dynamic range, like the Bartok piano concerts conducted by Pierre Boulez and the second Mahler symphony by Simon Rattle. Never is there the need to turn down the volume, the loud parts having no harsh edges at all, at the same time you are absolutely overwhelmed by powerful orchestra crescendo's. I know out of my own experience with other DAP's I was never able to hear these complete works without getting exhausted or turn it off once or twice while playing them. The C4 only let you beg for more. Relevant enough these days, where compressed and deformed audio seems to become the standard in both broadcasting as sold music. So, these are my impressions of the C4 today, feb 2015, about relevancy of this outstanding player. I can only say, buy one of you can, it might be relevant for decades of your musical experience to come.
Oh, and about the factors that were not in the main focus of the development team: UI-straightforward and good, Weight-doesn't easily slip out of your hands, so great, battery life-5 to 6 hours more than good enough for me, though I would love a battery life that last a lifetime!! and design, well when you find the best DAP ever, you want it to look unique, don't you