So, I rented a head and cab to gig with. I don't know much about these things. It's a Yamaha B100-115 III with a Trace Elliot 4x10. Now, when we were playing on saturday, the distortion was horrible. But to be completely honest, I have NO idea how to make it loud and clean. It's a rental, so I don't want to break it. How do I make this thing loud and clear. It has a volume section and two paramatic EQs. Also, what does the crossover do? Help! Thanks.