Hifiman HE-R9 ís the newest dynamic driver model by the leading headphone manufacturer in the world, Hifiman. It's a closed-back headphone with a Bluemini R2R Bluetooth module and it comes at $749.
The Drop + Hifiman R7DX is another collaboration between Drop and the biggest player in the headphone market, Hifiman. It is a closed-back full-size headphone using a Dynamic Driver. The price is set at $149.