I don’t really have any particular recommendations… but the trick for EQ is mostly knowing what frequencies to boost or cut.
This photo is a great reference:
https://twitter.com/BandPage/status/229948614368186371/photo/1
The trouble with something like a piano or keyboard is that is pretty much spans a large frequency range. You could start with a low pass filter around the 4-5000 Hz mark to cut off the high frequencies, and a high pass filter around the 30Hz mark. But I’m not sure how much that is going to help… EQ is a bit of an an art – it can be fun to play around with the settings.
Hopefully that helps point you in the right direction!