The Colorfly C3 sounds great, but it has an unfinished, "beta stage" feel to its software. I think that is unacceptable. If you can tolerate the menu typos, the weird UI, the popping and clicking between tracks, and the sluggishness, then it is a NICE-sounding audio player that gets out of the way due to its simplicity. There is something about its sound that is totally different from my other DACs and headphone amps. I would describe its sound quality as "lonely", "super clean", "sharp", and "cold". There is nothing behind the sounds. I guess that's what people refer to as a "black background".
The SABRE9018C2M SABRE32 on my V10 sounds "bigger" and "warmer", but it lacks the "snappiness" of the C3's sound, and also sounds too close for comfort compared to the V10's MSM8992 audio. I'm not a DAC head, and I'm the first to admit, "this does not sound anything special" if I was expecting audio bliss from a product...but the C3 makes me smile, even more because it is so affordable. It is my favorite audio gadget, especially for what I paid here on MD. I'm considering the C4. God bless you!
PS: The volume goes to 40 and at 25, it is perfect for me at home on my Audio-Technica ATH-M70x, Technics RP-DH1250-S and Sennheiser HD 239 and HD 598 SE. I can enjoy my Beyerdynamic DT-990 Pro 250 comfortably if I set the volume to 33-35 depending on the track. I leave the EQ on Normal most of the time, but I have to admit I really enjoy how it sounds on Jazz.