First, the principle of reducing music quality through Bluetooth wireless transmission audio technology is compression. The audio quality is lost during the decompression and decoding process after compressed transmission.

Second, no matter what format or bit rate the audio file is used, it will be compressed as long as it is transmitted through wireless transmission.

Third, in theory, an external APTX transmitter can achieve higher quality than traditional Bluetooth, but the power supply and transmission stability need to be verified. After all, this is a non-original external device of the mobile phone and does not power the mobile phone. Definitely not supported.

APTX is a form of encoding. Although I don’t know much about it, I know that this transmission method also improves the audio decoding delay through low compression rate. It can be said to be the closest to lossless. But it's not lossless in the true sense.

Explain it in another way. The distance between the faucet and the water tank is 10 meters away. The wireless transmission method is to spray water into the water tank 10 meters away. The wired transmission method is to connect a water pipe to spray the water. Pour into the water tank. Which method do you think has the least water loss?