No backing tracks. I already own a mixer. Small rooms. I care about the bass not sounding thin but it doesn't have to sound massive, just balanced. I tend to buy everything second-hand, but it's not a religion for me, so out-of-production products are fine as are in-production products. I prefer stereo sound from the piano but a single speaker "as a starter" would be okay.
Right now, we're playing through a Motion Sound 200s keyboard amp on the floor but pointed up 45