Amazon.com: Sennheiser HD 650 - Audiophile Hi-Res Open Back Dynamic Headphone : Everything Else
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...]
HD 650 | Sennheiser
Sennheiser HD 650 Reference Headphones | Reverb
Amazon.com: Geekria Headphones Case Compatible with Sennheiser HD650, HD600, HD380, PXC450, Sony MDR-XB200 ZX700 MDR-7506 V6 V700/ Headphone Full Size Hard Shell Large Carrying Case/Headset Travel Bag : Electronics
Review: Sennheiser HD650 – Answering Questions About This Perennial Classic - Headphonesty