Josè,
give a listen to the Ketron Midjay: there are demo's on the italian website; granted, they are just MP3s, but if you compare them with the MP3s from the SD1, the difference in sonic fidelity is clear.
http://www.ketron.it/demos/index.asp?idProdotto=22
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Korg Kronos 61 and PA3X-Pro76, Roland G-70, BK7-m and Integra 7, Casio PX-5S, Fender Stratocaster with Fralin pickups, Fender Stratocaster with Kinman pickups, vintage Gibson SG standard.