"Going direct" means he expects to take a signal from your bass and take it direct to the P.A.; the onstage amp is there for your monitoring. IMO, the WORST part of this arrangement is that your sound is completely at his mercy. As others pointed out, chances are his idea of a "good" bass sound are pretty far out of sync with yours ("ours", in all likelihood, being brothers in bass-itude.)
I say the best way of avoiding all that is to make sure the ONLY way of getting a signal from your bass is via a microphone -- nothing else, nada. Use your AMT, bring a mike, or use one of their mikes, but leave your pickup and direct box AT HOME (or in your gig bag.)
The sound guy is trying to do his best and probably knows a fair bit about what he's doing. The last time I had this situation (just about a month ago) I saw a guy I've known for decades sitting behind the board. Thought I was in good hands. At soundcheck he took my pickup signal, brought it through the mains, and he smiled and said "that sounds wonderful!". I was credulous enough to believe him. I had just recently started recording all my shows and, when I played back this show, I had about the worst bass sound you could imagine. If I was trying to get across a dead generic boomey slab sound it would have been OK. I was, however, trying to get across a rich double bass sound. My take away from that? NEVER AGAIN. Only microphones. At the very least it's the sound of my bass he's starting with.