Reply to S4 Sound Issues

Have you guys had any sound issues with your S4 at a club or bar? Last week I used my S4 for the first time at a bar. I basically plug into their house mixer then just do my thing but last week I started up and it sounded like the woofers were going to blow up it was so distorted. I have only been DJing since November and had been using a VCI 100 MK2 at the same bar for the last 3 months. Any suggestions?