Ok, this is going to sound stupid, especially for someone who's been playing for almost three years, but I don't know how to use an amp. Since I started playing, I've been using an old amp that only had volume, bass, and presence knobs. But I'm getting a new Peavey TNT 115 tonight, and it has a lot of stuff on it I don't understand. For example, it has pre gain and volume. I know that pre gain is when it boosts the volume before the signal is processed, but what does that mean to me? Which one should I control the volume with? It has a line out for an XLR cable. Is this for plugging into a PA system? Contour switch? Bright switch? Post EQ effects loop? What are these? Thanks for any help.