HD 599 & 599SE on sale on Amazon for prime members (link in comments) : r/ headphones
Amazon.com: defean Replacement Velvet Ear Pads Compatible with Sennheiser HD 599 SE HD 598 SR HD569 HD559 HD595 PC360 PXC450 PXC350 PC350 HD380 PRO HME95 G4ME Zero Game Headphone : Electronics
Sennheiser HD 599 Open-back Around-ear Audiophile Headphones | Sweetwater
Amazon.com: Sennheiser Consumer Audio HD 599 SE Around Ear Open Back Headphone - Black : Electronics
Amazon.com: Sennheiser Consumer Audio HD 599 Open Back Headphone, Ivory : Electronics
Amazon.com: Sennheiser Consumer Audio HD 599 Open Back Headphone, Ivory : Electronics
Amazon.com: Sennheiser HD 4.50 SE Wireless Noise Cancelling Headphones - Black : Electronics
Amazon.com: weishan HD598 Coiled Audio Cable Replacement for Sennheiser HD599, ATH-M50X, ATH-M70X, in-line Mic Control Headphone Cord Works on PS5 Xbox One 8ft : Electronics
Amazon.com: Sennheiser Consumer Audio HD 560 S Over-The-Ear Audiophile Headphones - Neutral Frequency Response, E.A.R. Technology for Wide Sound Field, Open-Back Earcups, Detachable Cable, (Black) (HD 560S) : Electronics
Amazon.com: Geekria Audio Cable Compatible with Sennheiser HD 599 SE, HD 599, HD 598, HD 598 SE, HD598 CS, HD 598 SR, HD 560 S, HD 400 PRO, HD 579, HD 559