yeah, I was referring to its soundstage. When I switched from DX50 to S:flo 2, everything sounded much wider, more spacious, and I could hear more details from the singer's voice.
I am afraid that I can't do a comparison with a full size headphone since I don't have one, but I can borrow one from the store.( I can do this only on weekend though...)
I think DX50 is decent enough as a portable audio player, the build quality feels solid, its touch screen is very responsive which easily puts S:flo 2 to shame. But I did find some flaws, when I pressed the physical "play" button on its front, it didn't respond immediately as I had expected, the delay of the response was too long for one to be unaware of. Beside this, I also found that it took a bit too long when loading a song from other directory (I was using microSD card and my music was classified by artist, each artist had one folder).