It sounded good out of the box, but there was certainly tweaking necessary to optimize it to my best use. In fact, it's still going on. However, virtually none of my tweaking had anything to do with the sound, it is mostly adjusting style part levels or changing sounds to better fit certain songs.
As I've mentioned before, the PA800 I bought was literally the first one to hit the U.S. The Rep handed it to me personally. It sounded awful. After I sold it Korg did a major overhaul of the OS and I'm told that it totally changed the sound of it.
Having said all this, I really believe the PA3X is a major step up from PA800. For sure it is from the one I had!
DonM