As for build quality, unfortunately here the 846 is far and away better than the W60. The build quality on the W60 is a disgrace for a $1,000 product. It feels like a piece of cheap plastic and lo and behold it is a cheap piece of plastic. Contrast that with the superb, precision engineered 846 and the W60 falls very short.
Yes plastic gets a bad rep when really it is about implementation. The SE846 oozes class and engineering in hand despite also employing an outer plastic shell. The transparent case is a thing of beauty. You can marvel at the drivers inside, which do touch the walls. Everything is tight and feels robust. What you get is a sense of reassurance. Step-up from the now-sold SE535 - itself no lightweight and worked like a dream for a touch over 2-years