What's their sensitivity rating?
That will determine how "loud" they will be given a specified input.
Also, they are rated for75 watts RMS. While this is more than your amp can deliver, it still ain't a heckuva lot. That 200 watt figure is for momentary peaks.
Finally, if you do try to drive 'em "loud", you run the risk of over-stressing your amp. While this may or may not hurt the amp, the distortion levels produced could possibly harm the speakers.
PA speakers are designed to cover the maximum area with a limited frequency range, not necessarily for "loud".