I haven't done a field test yet, but I imagine my amp is going to be pretty loud. Unless you're in a very quiet room, a lot of ambient noise (street, crowds, etc.) is going to cut through your amp.
What you should do to test is record a section of dialogue, and tweak that particular section until you're happy. Then when you go live, you don't need to worry about how it sounds, because when your helmet is on, your own voice will not be heard - but you will know how it sounds out the amp. Be sure to have your mic nice and close, and your amp loud enough to cut the ambient noise.