Sony's MDR-EX650AP in ear monitors use brass housings to minimise distortion and wide brass ducts for high sound stability. The brass housing used in these earphones resonates less than housings made from more traditional materials for clearer mids and highs + smoother low frequency sound.
Wish I'd come across these earphones sooner after buying many different ones over the years, even Sony, but these ones top the lot so far. Excellent sound quality with better clarity and handle the high bass levels that you get with Sony phones with ease and most of all very comfortable to wear as they sit in ears without having fidget getting them into perfect position. I highly recommend these and will definitely buy them again if need and must say these will work better in a Sony phone as thats what they are made for.