Sennheiser HD-650

I purchased these in 2017 when I decided to build a modest headphone system. I would say I got about 50+ hours of listening time before I decided to upgrade to the Focal Elex (Massdrop). I kept both sets for some A/B testing. I decided to stick with the Focals. 
I will include an aftermarket cable (5ft) with a balanced 2.5mm TRRS termination suitable for DAPs such Astell & Kern, Onkyo, Fiio, etc.  

With the HD 650, audiophiles will experience truly unique natural sound. With sound this good, long concerts in the comfort of your home are a certainty, so the HD 650 also sets standards in comfort and convenience. The HD 650 is a genuine masterpiece, which will satisfy even the most demanding listener. HD 650 – the Reference Class.

• Balanced & transparent sound
• Elegant titanium-silver finish
• Optimized for hi-resolution recordings
• Made in Ireland

Learn more about the HD 650

Features a specially modulated connecting cable (detachable) made from highly conductive OFC copper, Kevlar-reinforced, with very low handling noise, i.e. low structure-borne sound sensitivity.

Features

• Top-of-the-range open, dynamic hi-fi stereo headphones
• Systems with narrow tolerances (± 1 dB), hand-picked in pairs
• High-quality titanium/silver finish
• Neodymium ferrous magnet systems ensure optimum sensitivity and an excellent dynamic response
• Exceptionally natural, spatial and accurate sound
• Can be directly connected to stationary hi-fi components of the highest quality, in particular SACD, DVD-A and CD players

Frequency response: 10 - 39500 Hz

Impedance: 300 ohms

Transducer principle: Dynamic, open

Sound pressure level (SPL): 103 dB

THD, total harmonic distortion: 0.05 %

Weight w/o cable: 0.57lb (260 g)

Contact pressure: ca. 2,5 N

Ear coupling: Circumaural

Jack plug: 1/4" / 1/8" (3.5/6.3 mm) stereo

Warranty: 2 years