okcsc 0.78/0.75 2 Pin Cable Adapter Work for 0.78/0.75 2 Pin Connected to Sennheiser HD414 HD650 HD600 HD580 HD565 HD545 HD535 HD525 HD265 HD25 Headset Connector Black
Sennheiser HD525 -> HD650 for $106. :) : r/headphones
Amazon.com: Geekria QuickFit Audio Cable Compatible with Sennheiser HD 560 S, HD599, HD598, HD 598SE, HD 598CS, HD 598SR, HD579, HD569, HD400 PRO Cable, 2.5mm Jack AUX Replacement Stereo Cord (6 ft /
3.5MM Premium Audio Upgrade Cable Replacement for Sennheiser HD525, HD580, HD600, HD650 etc. Headphones (4FT)