I suspect that you may need to set the global EQs a bit to achieve the sound quality you wish to achieve. To me, the S-910, fresh out of the box, is very flat sounding in comparison to the Tyros2.

If you have not set the global EQs yet, press the Mixing Console button, tab to EQ, scroll down to User1, the press the Edit button. Try the following settings: EQ1=5, EQ2=4, EQ3=2, EQ4=4, EQ5=8 and see if this makes a significant difference when played through the onboard speakers.

And, of course, with the Tyros2, there will be some differences with the sound system used as well.

Hope this helps,

Gary