The PV series is not that high of quality...having said that, you probably need more power to clean up the distortion. As the Sweetwater sound techs say, double the continuous power rating for the speaker is recommended. This will allow clean udistorted signal to the speakers. I found this out the hard way as I blew the horn in an SP-5 by pushing a 300 watt signal at it. Although the speaker is rated at 400 continuous, the amp was clipping, and it destroyed the horn. Hard lesson to learn, but more power (and unfortunately, more money) is required to get a good clean sound. Over power with a clean signal will not hurt a speaker as bad as dirty under-power.....Keep rockin
The reason you are distorting so bad is that your amp is severely underpowered. Nothing kills speakers more quickly than distortion from an underpowered amp. For your set up you need an amp that pumps at least 800W@8ohms per channel or 1600W@4ohms per channel. Or twice the wats at the same impedance. You should have a separate sub. Ahhhh don't forget to get yourself a Driverack PA, that thing is amazing.