boss ac3 volume problem

[shed dweller]

I am using a telecaster through a Boss AC3 acoustic simulator, into a Fender 250W PA system and getting nowhere near enough volume. Please can anyone suggest a way of boosting the signal from the Boss AC3 without changing the sound. Do I need a preamp and if so, which one?

[cjlectronics]

What output are you using; the line out or the G. amp out?
Do both outputs produce the same low volume?
Do you have the user manual?