I have a Xiaomi redmi note 3 pro. It's a 5.5inch smartphone. I now rotate it in between my eyes so that the 8.7mm side is right between my eyes and up close. This is the best I can do to describe the hd660s staging. It is a line almost that thick in between your eyes in the middle of your head with a decent amount of depth. It is rounded at the edges more than any other hd6x0. While it is probably was the most dynamic and has the greatest sense of clarity and texture amongst them while retaining the mid timbre. It was the most forward and shouty. The staging and short decay made it very hard to listen to and very nauseating. My impressions are short because it did not jive with me at all. While I love my hd580 and this keeps most of that mid timbre with greater technicality. It's other aspects make it a far more polarising headphone which isn't as safe to recommend to newcomers who don't know their preferences.