The answer is yes, you can synchronise the sequencer playback with the audio playback from SD.

The "Getting the most from your KN7000" book has half a dozen demo tracks on the CD to load onto the SD card. Some use 7000 created backings, including the 'strumming guitars' but most of these use audio backing tracks of a real orchestra; real brass, real strings etc etc. The melody from the KN7000 sequencer plays along with the real orchestra, along with a slideshow of the rolling music score in the screen. You can switch the melody off in the sequencer and play along yourself live with the real orchestra using the KN7000 voices and still have the rolling music score in the screen to read the melody, all perfectly synchronised with the music.

Thus the possibilities are endless, if you play acoustic instrument and KN7000, you can duet with yourself by recording the acoustic instrument onto the SD card, then play keyboard.
You could use KN auto-accompaniment backing or use a karaoke mp3 orchestral track for backing.
As I said vocal or choral backing is an ideal application for SD audio playback.

Basically any audio multitracking for which I needed a laptop, portable flash or hard drive mp3 player or cd player to play along with before can now be stored on the SD card requiring only the KN7000 for playback.