From the Tyros manual and what I've read in other places, I get the impression that you cannot select or use the MegaVoices at all, even in creating your own custom styles. You can immitate a MegaVoice though. If I'm right then a MegaVoice is just a stack of existing individual sounds on the Tyros seperated by velocity zones. Example: an acoustic guitar MegaVoice could have the following individual voices in it: acoustic guitar (possibly seperate voices for high and low tones), acoustic guitar pluck, ac. gtr harmonic/overtone, slide noise, etc. You can select and play those individual sounds yourself, sequence with them, and create custom styles with them by assigning each sound to a midi channel and using lots of midi channels... say five or six to get a psuedo-MegaVoice guitar. And instead of using six notes of polyphony to make a six-string acoustic guitar you might use far more. Yamaha can use the real MegaVoices to get all of those sounds with just one midi channel and probably has a custom sequencer/style creator program and/or a specialized controller setup for preventing overlapping sounds, thereby freeing up more free midi channels/memory/polyphony for other sounds when the MegaVoices are used in performance. This would have the clever side effect of making you rely on Yamaha for more styles that take full advantage of the MegaVoices. Or I've totally missed the boat here and sank to the bottom of the lake...