The PSR9000 Pro doesn't have speakers, but the PSR9000 does!
I don't know what the price difference is between the second hand PSR9000 and a the brand new PSR3000, but if soundquality is important to you, I would go for the PSR3000.
Check the yamahaPKClub site, where you find the update software for the PSR9000. There is also a manual addition for version 3 on that site: click here .
There is also Pipeliner's site about the PSR9000. I suggest you download the PSR9000 and PSR3000 manual and if possible, play the keyboards.

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drdalet