I just got in some PSRS770 keyboards and noticed on the back the same 1/4" mic/guitar switchable input with gain control. The PSRS750 did not have this. Singers and guitar players can use this feature like on the 970 although it doesn't have the vocal harmonizer but you can use the built in effects to add reverb, etc. A guitar player can add distortion, wah-wah, etc. Many players don't need the harmony but do like being able to plug a mic into the keyboard and sing through the speakers or go out through line outputs.

A guitar input is very cool.

Hi George, thanks for the "direction".
I have rented a 770 for two (2) months from Long & McQuade in Toronto, Canada and after just 2 weeks I'm hooked already.
Have a Happy Halloween weekend in the West Valley.
Sincerely,
David Patt