I've recently upgraded from my trusty old pair of Sennheiser CX300's to a gorgeous set of
Klipsch Image X10 and I've been blown away by them.
The difference between the two earphones is staggering. There is so much more detail present with the X10's compared with the CX300's.
I'm guessing this is also true of earphones like the Sleek Audio SA6 and the triple driver UE's and Shures. I'd love to hear a pair of triple driver earphones though to compare with the X10.