I’m liking the pristine, clear, clean sound of the styles and voices of the SX 900. Don’t know what they did, but the bass parts and drums are more distinct, especially in recording. Really like the choral voices they added. Would have traded up for those alone. Finally getting the vocal harmonizer to my liking. Like others have said, you must tinker with it a while to get it to meet one’s preferences. Hope the SX models are big sellers for Yamaha in that maybe, just maybe, with future models, they will provide more trickle down features from flagship models------so that buyers (like me) who prefer smaller, lighter keyboards (with speakers) can enjoy a high-end professional sound that’s not too costly.