So I was gonna get a mixer to use live with my band, it would be for mixing 3 or 4 microphones that then go into a pa speaker. Would I need a mixer with 3 or 4 mic preamps (one for each mic) or could I do without mic preamps and just plug the mics into the line level inputs? Could I just mix all the mics at mic level then put a single mic preamp after the mixer? Also do mixers with mic preamps need to be powered?