That will depend on you. I typically run mine full throttle with a mixer to control the gain. I NEVER get distortion, but that's an idividual situation. You need to balance your signal in the kb first, and then send a good, strong signal to the speakers. It will provide plenty of gain for you.

For times when I leave the mixer in the van - I set the main at about 3/4 and it's usually enough, since these are smaller venues if I leave the mixer out.

For large jobs where the bass needs to "thump" I send a second (mono) signal out of the mixer to a bass amp, and roll off the bass a little in the EV's - works like a poor man's crossover and produces almost the same effect ! It's all in the balance. Use your ears, and you'll be fine.