ATKs aren't a very "hot" active bass stock. I've heard there is an internal pot that allows you to up the juice of the preamp. I like mine where it is, so I haven't gone snooping yet.
This is correct - it's easy to find and adjust. I run mine at about 85% on (near as I can figure) for a good hot signal into my Tech 21 amps. Makes my distorted channel really howl