Archimago's Musings: MEASUREMENTS: Sennheiser HD650 (~2010-2012) and HD800 (~2010). A comparison of two "Reference Class" headphones, and a look/listen to the "Sennheiser veil / darkness". [Inexpensive 2TB SSD and inflation in consumer electronics...]
Headphone Test Lab test results manufacturers sennheiser hd 800 s
Sennheiser HD 800 S Open-Back Dynamic Headphones | Bloom Audio