I always thought Yamaha psr models sound "thin".
I now have an idea that Yamaha's sound is initially adjusted in order to sound well on majority of speaker systems, including internal speakers, if the keyboard has ones. What I mean, my PSR's recordings sound fine even when I play them with iPhone's speaker, but when I play the piano which I recorded with my Roland, on a small speaker this reach sound gets very distorted.
Yamaha ballances all its instruments to sound well in the mix..
Roland ballances the mix for its backings
This allows, for a way less compressed sound of solo instruments..including piano..
however on my Jupiter 80, you can easilly solve the problem by adding a bit of EQ/Filter/compressor to the piano sound..
On the other side of things, this makes the piano sound on the jupiter 80 extremely suited for solo playing with all its harmonics...