My church did the same thing several months ago along with backing and click tracks through Beringers. I can't afford IEMs so I use headphones. The sound is terrible but as long as it sounds good in front of the stage I'm OK with it. I'm old school and would prefer to use on stage monitors with my own amp behind me. The sound man always tells me I sound fine. As long as you sound good out in front of the stage then don't be too too concerned with how you sound in the OEMs. As long as you can hear what you are playing you will be fine.
