"My argument is that people who is willing to spend around $400 for a DAP most likely already have a preferred Ear/Headphones so not sure whats the target market here."
 
Or maybe spend a little more and bundle this with the RE-600s in a way that would provide a little bit of an overall discount for what would probably be killer sound.

Just buy Fiio 5 3gen

@mike138 Well the bundled IEM is said to be very similar to RE-600 (I don't know because I haven't listened to them), and I can confirm that they do have a very good SQ, so I still believe it's a good value for $400, however personally I would like the options to choose
 
@qafro I haven't heard the Fiio X5 iii and I am sure they're amazing knowing Fiio track records, however the Supermini is quite light and small and that's true portability IMHO