I hooked up my friend's 740 through my 2 JBL powered Eon 15's so he could hear what it really sounds like. It sounded great. Not as great as the X1, but then nothing much does.
I used a Mackie 1202 mixer, but very little e.q. was necessary. The mixer allows you to control the keyboard volume if you set it close to you. The 740 volume knob does not affect the line outs, so you have to do it this way, or assign the volume pedal and use that. I prefer the volume pedal be assigned to the lead voice. You could also control volume by adjusting the speakers' input, but not practical to do that during a performance. The Mackie has XLR balanced outputs and you just use standard mic cords from the mixer to the Eons.
The seperate amps for bass and high-end really brings the keyboard to life.