Very sorry, lots of head-fi'er known that X3 is designed before E17, the build quality of X3 is not as good as E17, but the SQ is better than E17.
although we have the ability to make a more better X3 in build quality, but the time is not enough , also the cost will increase too. hope you can understand. but for X5 , it will represent our best ID in 2013.
Does X5 offer a true LINE OUT? Does it play 24bits FLAC file?
What is the X5's battery life comparing to X3?