Well, I've used a couple different Mackie Boards, one with 16 channels and one with 24. There is a Headphones volume tuner on the right hand side of the board, that should be up at least half-way. Second, main mix s/b Unity Gain, Keyboard channel s/b...
Cerwin Vega, JBL, York, Mackie, EAW, Yamaha, Sonic, and if you want something for a more reasonable price Behringer speakers sound good
Run them through your mackie board so you can adjust them so one doesn't overpower the other.