I've got a beauty pageant Saturday , the promoter tells me there is going to be "a surprise celebrity performance" it'll be a guitar . The promoter knows nothing about sound and I can't get ahold of the surprise celebrity . I was told the guitar player will just walk out on stage and plug his guitar into the sound system . I have XLR jacks onstage , I operate from a booth , back of house , in the ceiling . I'm assuming he'll use a DI . I've never used one before I always use a wireless transmitter for line level sources . I've heard there are both passive and active DI boxes . If I just leave the phantom power on for the input he'll plug into , will a passive box ignore it like a dynamic mic will ? Thanks