| To do this properly you need a microphone split feed. If this is agreed with the band, you need to approach the PA company to find out if they can/will give you a split. If it is part of a festival/venue and the PA is hired by the venue/promoter you will probably be out of luck, however if it is a PA hired by the band then they can either ask the PA company for the split or you can hire a split that you can use with the PA company. Either way you will need to discuss this with the PA people.
Regards
Roland |