The only reason I use this trick is to obtain 320kbps mp3s for songs that are hard to find.
1. Download Audacity on a desktop
2. On your phone, navigate to your desired song on Spotify, but don’t start it yet. Turn your volume to the max for best results.
3. Get an aux cable. Connect one end to your phone, and the other to the line-in jack on the back of your desktop. This will most often be the jack with the blue outline.
3. Launch Audacity. Go to edit -> preferences -> devices -> recording -> and select “Line In” from the devices dropdown.
4. In quick succession, press the record button in Audacity and start the song on your phone. You will see Audacity start to record the music.
5. Only once the song is done, press stop in Audacity. Delete anything that you recorded before the song started. You can zoom in to pinpoint the exact millisecond the song began. Do the same thing for anything recorded after the song ended.
7. Go to file -> export audio, and save your file with your desired settings.