Ola!
Unfortunately, I didn't totally dig the Grado experience. I do miss its representation of Satriani or Malmsteem but I realized that my ears like more POW! (bass

.
HD660 came to the rescue. Sastisfied with SQ? very! A good all-rounder. However, I haven't read a comparison of this cans with the HD661 and I feel a lot of people in the interwebs are looking for the face-off.