Sennheiser HD 650 Headphones $424.15 Delivered (Was $799.95) @Sennheiser eBay

Features:

Open-back dynamic headphones
Special damping element made from fine acoustic metal mesh
Exclusive 42 mm transducer and 38 mm diaphragm
Lightweight, timeless design and comfortable velour pads for hours of fatigue-free listening
Frequency response: 12 – 41,000 Hz
Go-to reference for analytical listening
Extremely tight production tolerances (± 1 dB) and handpicked components
Detachable connecting cable made from highly conductive OFC copper
Impedance: 300 ohms
Total harmonic distortion: <0.05%

Sennheiser HD 650 Review:
https://www.rtings.com/headphones/reviews/sennheiser/hd-650