The HD-555's would likley have better detail and soundstage. But you have to remember they are open air headphones, not closed or sealed. The super-fi is an IEM, made for isolation and portability. If you want pure performance, get an open air can like the Senn or Grado or something.
As far as the best sounding IEM's, Shure is known for its midrange sound and recessed lows and highs. Super fi's are warm and sparkly sounding, and Etymotics are kind of a more balanced but not as musical sound and "colder" sounding then the others. Its all your preference.