・Song audio is sent using the left channel of the smart device stereo output, while the melody and chord data is sent on the right channel. You can then play along to the song and use the step-up lesson function. You can transfer and save the song's right-hand melody and left-hand chord data, or the left-hand performance data, to the keyboard. The notes and chords for the melody are shown on the keyboard's LCD. When a song is played, the light-up keyboard shows the left-hand part and the melody. Use the keyboard's light-up function and practice step-up lessons directly on the keyboard itself. The keyboard link function enables you to use an audio cable to send melody and chord data along with the audio playback. Stereo mini to stereo mini cable required.