Never had original 8xx cables to check but I would be surprised if they weren't the same.
Never had original 8xx cables to check but I would be surprised if they weren't the same.
HD 559: https://assets.sennheiser.com/img/18214/product_detail_x2_de...
HD 650: https://images-na.ssl-images-amazon.com/images/I/61vm4c%2Bhb...
HD 660 S: https://assets.sennheiser.com/img/25816/x1_desktop_sennheise...
HD 800 S: https://cdn.mos.cms.futurecdn.net/cVSs2jBo28NYKPkdGtZhnR.jpg...
I'm not seeing a lot to back up your claims. Especially since a lot of those headphones come with a 6.3 mm to 3.5 mm adapters.
Edit: the 3.5mm male to headphone is Sennheiser 81435 [0] the 6.3mm male to 3.5mm female that fits over it is Sennheiser 562507 [1].
[0] https://en-us.sennheiser.com/cable-3-m-35-mm [1] https://en-us.sennheiser.com/accessories--adapter-jack-63s-j...