Sennheiser MM 550-X is an upgraded version of the previously recommended 500-X. The biggest upgrade is to try the latest Apt-X Bluetooth transmission. Even wireless Bluetooth transmission can provide high fidelity audio quality. There also seems to be more powerful NoiseGard technology, which has better noise reduction effect.

Sennheiser MM 550-X is 50 dollars cheaper than the last recommendation. The historical price is 247.49 dollars, about 1500 yuan. The price is expected to be settled within 1700. The price of domestic goods is 4000 yuan, so the price advantage is very obvious.