Domestic new 4000 supports AUX and USB audio input. The USB socket is under the armrest 12V power supply. It says AUX, and it has a cover. You can see it when you open it. You said you want to use an SD card, so you have to buy a card reader (it's sold everywhere, just a few dollars but not more than ten dollars). Save the song, plug it in, and then turn on the stereo. There is an "AUX" on the central control. USB button, just press it. To make you understand, I'll give you a description of the whole picture. Ha ha laugh