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 has a historical low price of $299.25, about 1800 yuan, which is not much more expensive than the previously recommended 500-X. The price is expected to be settled in 2000. The price of domestic goods is 4000 yuan, so the price advantage is very obvious.