Not sure what to call this, so I'll explain it. I've seen in some cases, when a keyboardist has two keyboards they are using. They put the top keyboard on strings and leave the bottom keyboard on piano. It is patched (I guess that is the word) together so when he/she plays the piano, the strings play along, but when he/she turns the volume down on the top keyboard, they just have the piano sounds. In other words, they are able to fade the strings in and out, whenever needed. Does anyone else use this effect? If so, how do you do it?