Build quality seems good but not great. However, RHA does offer a three-year warranty on these guys, which is a couple of years longer than what you get with most headphones.
As for their sound, these headphones are more bound to please audiophile types who prefer well-balanced sound that doesn't accentuate the treble or bass. The SA950is offer smooth, clean sound, with good bass, but they're not incredibly detailed nor do they deliver incredibly deep, powerful bass despite their 40mm drivers. Speakerphone performance was fine.