Massdrop offers preorders of the Massdrop x Sennheiser HD 6XX Headphones in Midnight Blue for $199.99 with free shipping. That's tied with our mention from last month as the lowest price we've seen. (It's also $115 under the best deal we could find for the similar Sennheiser HD 650 headphones.) Deal ends February 27. Based on the classic Sennheiser HD 650 Headphones, these extremely well-reviewed open-back headphones feature the same drivers and architecture, updated with a 6-foot detachable cable with 3.5mm plug and midnight blue colorway. They offer a 10Hz to 41kHz frequency response, 300-ohm impedance, and aluminum voice coils. Note: They have an estimated ship date of July 13.