I've been delving into sound design / editing on both my Korg Pa700, and Tyros 4. It's quite a deep subject but can change the characteristics of a sounds. I've been quite impressed by the set created for the Korg Pa4x
http://www.quirobinez.nl/
It shows how a flat sound can be turned into something amazing. But even small changes to a sound can make a world of difference.

Hi James,

I agree that its a very complex subject I dabble a little since getting my Korg Pa700 as with Korg you can do a lot more sound editing onboard without the need for external software as you do with Yamaha, I hope to do more when time allows, Thanks for the link

Brian007

Yes the Korg Arrangers have subtractive synths built in.