The advantage of using the SD Audio feature is not for everyone I guess... I would say it is rather useful for people who go out for gigs and need extra 'live voices' to accompany them while singing and playing the KN (like I do with my partner).

The beauty of it is that when I go out for a gig, I only bring my KN, a small mixer to blend the KN output with 2 microphones, and 2x200 watts powered speakers.

Everything is on my 1G SD Card:

All the MIDI songs that I need to play live with 'real' back voices and well over 8 hours of dance music which I put on while we take a rest between sets.

And my SD Card is only half filled!

By the way, Bob, I used to own a KN2600 too, and the SD Audio Synchro was on it.