HD 800 S leads with a 56mm driver and 4 Hz-51 kHz response (per Sennheiser specs) versus DT 1990 Pro's 45mm and 5 Hz-40 kHz, creating a noticeably larger soundstage on RTINGS tests. DT 1990 Pro remains competitive for studio work with easier drive requirements and swappable pads. The 40 g weight difference favors the Sennheiser for extended listening per user feedback on forums.