This has now become my main go-to earphone, simply because of its simple, lightweight construction that is easy to put on comfortably, and a great sound signature that is revealing of details yet does not skimp on the bass. Overall, a very competent entry from Final Audio.
Right out of the box I can't hear the difference between E3000 and E4000 playing from LG V30 and Shanling M0. They both are smooth with decent soundstage and bass. They recommend 150 hrs of burn-in, though.
So, you can save some money, if there's no need for a detachable cable, imo.
I've had these earphones for a few months now and they're in as good of condition as the day I bought them.
I went from the E2000 to these and there was a noticeable separation in the instruments, the E4000 made my E2000's sound muddled. There was also an expansion of the sound stage, better bass, they're a bit warmer sounding but i prefer the warmer sound. I love the bass on these IEMS as well, it's very full sounding. All in all i'm very satisfied with the E4000 IEMS