Frans,
The PA2XPRO I have (going on 2 years now) sounds BETTER than the demos on the Korg site. Great keyboard...
I play mine thru a set of Mackie HR824's which are great powered monitors.
A lot will depend on your speakers...remember the old days of stereo HFI??? The amp was important (enough power to prevent clipping) BUT the speakers were everything.

Same thing here. (of couse there are other variables like Master EQ settings...on the PA the master EQ is OFF by default and it needs to be on and adjusted to suit you likings, and room)

Hope it helps...Lee S.