Can be changed, the combined sound structure is not complicated, simply speaking, there are two large pieces; 1, VCD digital decoding chip, 2, and adjustable power amplifier for output. If you want to play music with a USB flash drive or memory card, you need to buy an MP3 decoder, which is integrated with the USB flash drive memory card. It is only used to read the data in MP3, and then output it to 2, and then output it to the speaker with a post-amplifier. How to change this specifically needs you to do it yourself. I analyzed a few points for you, at least to prove it. .
The price of MP3 decoder is around 50 yuan.