I have a new Studio 68c, and a guitar with active pickups. When I read the manual, it appears to say I cannot plug that guitar into the instrument input or I risk damaging the 68c. It tells me I have to plug it into the Line input, which is XLR right? (I'm new to this). Can someone tell me, specifically, what I need to buy to be able to use a guitar with active pickups and the Studio 68c?