Reply #7: I always used a small (15") peavy amp

[lukasahero]

through my own mixing board but also ran direct out from my mixer to the main board. If you're mixing all your sound through a main system, this will work fine for keyboards - let the main speakers do the work but take one direct out from the keys - you don't want to give too much control to the sound man. ;)

If not, then he'll probably want to invest in a powered mixer and either a bass or keyboard amp big enough to match the sound of your guitars/bass/drums. That will vary according to the volume and style of the band as well as the venues you play.