Build Quality: The build quality is exceptional. I have owned my pair of Bose Soundtrue in-ear headphones for about a year, and they have been pulled on, sat on, and generally abused, but they don't seem to be at all worse for wear. The QC20s have a similar design, except that they have much thicker cords, so I am not at all worried about the longevity of this pair of headphones.   Comfort: The comfort is good, but not perfect. They do not sit quite as comfortably in my ears as the soundtrues (which are by far the most comfortable in-ears I have...