hello, it wanted to know which the main differences of the model one CTK-900 and of WK-3200 of casio (aside from the 76 keys, wheel, and other accerios external) I want to know if internally this two keyboards are equals the two have 600 tones 160 rhythms 224 tones of user etc and although there be various previous models al WK-3200: the WK-1200, WK-1250, WK-1300, WK-1350 WK-1500,WK-1600, WK-1630,WK-1800, WK-3000 Sounds and other things the CTK-900 and WK- 3200 they are exactly equal?, that recommend thanks.