Though smartphones can be used to listen to music, they can't compete with high-end music players. Toward the top of that list is Sony's NW-ZX707 Walkman.
...None of this is new? Portable, standalone DACs have existed for years. Even DSD isn't new. What Sony's charging isn't even out of line. Fiio charges (IIRC) $1200 for their Android-based player/DAC.