You might want to consider a camera with XLR inputs. This would give you balanced audio and where possible would allow you to get sound from the sound board. If that is beyond your budget then you could consider a preamp
( http
/www.juicedlink.com/ or http
/www.beachtek.com/ ). The only thing I can think of that may help with the camera you have is an external mic, that is, if you are not already using one. When you record the band is the camera static or are you moving around a bit?