Thank you again J'man! Actually I bought it as a B-stock from thomann.de since it was nicely discounted. They have mentioned it might present "slight traces of use" and they are guaranteeing for it for 3 years. My guess was that particular piano have been heavily used, and not just "slightly", prior of being returned to the shop, maybe as a demo piano or so, so I asked Thomann. They have replied that it has been returned in the "30 days return" policy, only once, and they (oddly) added that, indeed, the CDP keyboard is much sturdy and firm than PX-150's (although the price difference is significant...). But that was Thomann, not Casio :-) (They haven't mentioned the reason for being returned but it's worthless asking since their return policy doesn't require a reason for products to be sent back). Now I think in less than a month 30 days it can't be worn out so severely... I am considering to return it to be changed (it will cost me something...) but I said to ask some other owners/users first, maybe this is how it is! The more annoying is not the sound - passable if I turn the volume up - but the bounce in the upper register keys. If I press the key and depress it rapidly, it bounces two times before resting. So or it's not properly dampered or that's the "key feedback" as Casio thinks it should be. (The supplimentary noise is an effect of this bounce). Cheers! Cristian