Is there a difference in the key action? From the website http://www.arbitermt.co.uk/studiologic/88notekeyboards.htm it seems that they use the exact same weighted action key mechanism.
If this is so, then the only differences are some of the electronics, and the lack of a midi-in on the SL-990 PRO?
If this is so, then the only differences are some of the electronics, and the lack of a midi-in on the SL-990 PRO?