Bought IEM denon c710 in jaben before,& now I am hooked!

1) Now I'm looking for a headphone in the region of 700-900 (or just slightly more if the difference sonically is huge) Any good recommendations? I mainly listen to female vocals & rock,source iphone & laptop,FLAC,used solely for listening to music ( + maybe movies,but not games) . I am satisfied with the overall sound & bass in c710,& now I am eager to try something new

2) What portable DAC would pair well with Hippo Box+? my limit would be 500.

3) Any good quality mp3 around or < 500 region? I am thinking of clip+ but am still open for choices

Thanks!