Active Military and Veterans can get up to 30% off @ Sennheiser's website via
id.me. I added the HD660S to the cart and the discount was 30% off, making it $350.
Samsung website is also offering 30% off via id.me. BTW, there are a slew of other retailers from multiple industries (Electronics, Hardware Store, Travel, etc.) with some nice discounts ranging from 2% - 50% and even some freebies too. It's not only for Military/Vets, but you might also qualify if you're a College Student, Teacher, First Responder, Government Employee and Healthcare Worker. Might be worth signing up for with the holidays in full swing.
Good luck!