I've performed a lot of living room and family room parties, often using just the onboard sound system of the keyboard.
As for the EQs, keep in mind that men ages 70 and older lose their high frequency sounds, while females in the same age category tend to lose low frequency sounds. I think nature intended it that way so we can't hear each other nagging while driving the car and getting lost.
BTW: Knowing how much you enjoy stereo sounds, these jobs would be easily covered, in full stereo, with any of the inexpensive Logitech systems. If you decide to use the onboard sound system, you can project that sound forward of the keyboard by constructing some very inexpensive deflectors that resemble an air scoop on the hood of a hot rod car and fastening them to the speakers using small, Velcro strips. Not only does this deflect the sound forward to your audiences, but additionally, it tends to amplify the sound as well, while at the same time help eliminate any feedback problems.
Good luck,
Gary