Here is another track that does not go as high but has bombastic bass going on, and multiple singers even some male talking.Maybe W shaped might be a better way to describe it as if anything what's being described here seems to affect the upper mids more than the lower and U-shape to me implies the entirety of the midrange being subservient to the bass and treble. IE900 to me is a classic example of a u-shaped IEM...the EXT is not like this to my ears. I have some homework to do and a class to attend but afterwards I'll listen to the track @RTodd recommended and report back.
Kristy MacColl
Walking Down Madison
Off of Electric Landlady