Hi Uncle Dave,
Again I come to the defence of my beloved PSR9000, the bass is factory set in a neutral position, each part left,R1,R2,R3 and the eight style parts have their own independent Hi and Low EQ settings as well as a global EQ with the usual bands, if I need extra bass I just up the Low EQ on the style, at full setting the bass is just incredible, no distortion at all, even at high volumes.
I tested the PSR9000 speakers using some dedicated XG midi files containing both acoustic bass and electronic bass, with factory EQ setting bass is ok, but turn up the EQ on the song part and it's real floor shaking stuff, but not keyboard shaking, this is probably due the wooden speaker enclosures, they insulate the speakers from the plastic case.
The PSR9000 is definately not a keyboard to be taken at face value, it takes many months to realise the mediocre factory settings only exploit a tenth of what it is truely capable of, my PSR9000 is almost coming up to it's first birthday and it just gets better and better the more I explore.
Now I know I can get new Yamaha styles from ITALY that are at least as good as any of the competition I think I am in arranger keyboard heaven.
Paul.