On my Yamaha EMX212 powered mixer, I understand I can acheive 220W per side using a 4 ohm load. I get this from using the main+montor mode with 2* 8 ohm wedges on the monitors and 2* 8ohm bins for the mains. I would like to be able to use the main out jacks at the front via a separate power amp and speakers as these are supposed to be at line level. Am I able to do this safely or will this reduce load on the unit and cause harm to it?