For most people, Cowon J3 is pretty much the ultimate 'non-audiophile' music player for its sound quality, battery life, and expandable storage (I've heard of 64gb micro sd cards working on it, I haven't tried myself yet).
 
After having many Creative hard disk based DAPs(Jukebox, Zen touch, Zen Vision W), I wanted to migrate to flash based ones. As Creative simply became totally uncompetitive with audio players, I had to look elsewhere, by chance I stumbled upon Cowon, and I found J3 to be the perfect choice.
 
The sound is clean, clear, absolutely no hissing even with some very sensitive IEMs, and with BBE enhancement it becomes pure enjoyment for the ears. It also has an equalizer for more fine tunings.
The battery lasts long time, with regular commuting use, you probably will need to charge it every 2 weeks or so with sound enhancements on, more if every bells and whistles turned off.
 
Now the bad things, the cable is proprietary, I really don't know what Cowon was thinking while designing it, so if you lose it, you will need to order another one online. Good thing the battery will last long enough before your shipment arrives.
The UI is horrid for today's standards, Cowon seemed to have trouble designing one, it is very tedious to make a playlist work.
The prices are simply ridiculous for an aging DAP, and currently many online sellers bundle them with useless 8GB sd card to inflate the price further. Very deplorable.
 
Bottom line, perfect standalone player for commuting, gym etc, without the need of an amp.

I was someone who listen to a lot of electronic music, and tried many sub $50/100 earphones that are mostly bass heavy like CX300, EP630, Klipsch S4 etc, I was satisfied with their better than stock earbud sound.
One day I saw that one on sale and gave it a chance, since I've heard of BA having clear sound compared to dynamic. I was disappointed at first, due to the obvious weakness in bass, and I stopped using them for a while until I played around with my J3's EQ, adding bass and to my surprise, it is able to have adequate bass after all. Progressively I grew used to it, then when I switch back to these bass heavy earphones, they sound so much more muddy in comparison, I immediately missed the clarity that the C10s offer.