I've been experimenting with the little used "ambience" dsp, I find it gives the styles more presence, I've listed the precedure below, the style section uses DSP block 3, I know from reading this and other forums that some owners have problems activating it, so here goes:-
1. Choose a style, press digital recording button, select style creator, then full edit, press mixing console button.
2. Choose "EFF type" page, on the left of screen select dsp 3 and on the right select "ambience" (it's about the 20th preset effect up from the bottom).
3. Press the "exit" button, select the "store/clear" page and save as a custom style.
To activate the new assigned effect, press mixing console button, select "eff depth", press mixing console button repeatedly until the component sections of the style are shown, turn the "dsp 3" levels up 64, press mixing console until the main keyboard sections are shown and ensure "dsp3" on the "acmp" is set at a reasonable level, by turning the level on and off you should hear the difference the "ambience" makes. I have found setting "dsp3" on RHY1 and RHY2 lower than the rest of the style parts gives better results for some styles, store the setting as part of a normal registration.
Hope this is of use to PSR9000 owners.