Just curious...., are you wanting this for the purpose of a better solo piano or one that's not a solo instrument, but one that sits well in the mix?

I'll pass on a suggestion to you regarding a "piano in mix-not solo related". Often for pianos that sit well in a mix you truely don't need to use one of the better quality samples on your board. One thing that a lot of people do (myself included) is using the MONO piano patch on your keyboard (if it has a decent one). Mono piano patches really work well because (since the patch isn't in stereo) the sound output isn't so upfront and in your face. Before I could afford better gear I bought the Roland RS-70 (and I still have it even though I have other gear that puts it to shame).., but for a piano that sits well in a mix.., that Mono Piano patch I tweeked is my FIRST GO TO PIANO for this when using that keyboard. The overall sound is already pushed back.

If you're wanting that solo piano patch you'll have to dig into the synth parameters. The S900's layout is not difficult and like I said in another post.., in a very short time I edited a piano on the S900 (when I played it) and ended up with something to my liking.