There's a new model that's a solid body AB-II. Designed to be heavier than other models, but to really make the lows shine. It's called
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My AB-II is a fretless hollowbody and the hollow body gives it a really mellow, acoustic sound. It's great. And so, so light.
As for the preamp, Dingwalls mostly use very transparent-sounding preamps. They give you EQ flexibility without coloring the sound in any way. You can barely notice the difference between passive mode and the active EQ with no boosts/cuts. To me and to many others, this kind of preamp is useful but not necessary in any way.
I leave my AB-II in passive very frequently, for no reason other then to marvel at the sound that those pickups have. My Combustion, on the other hand, has a John East EBMM preamp and it most definitely colors the sound. For the better, in my mind, and that's why it's there. This preamp is always on and plays a big part in making it sound the way it does.