Really acoustic or a bunch of acoustics miked and DIed?
Totally unamplified you need a deep body and as much solid wood as possible in the body...definitely the top, back and sides as well is even better. There's a
huge difference in volume between an ABG and a DB and it's because of the body size. I have played totally unamplifed gigs with my DB, they would have been impossible with an ABG.
I've been interested in this bass from Rigel: $2500 Have yet to see or hear one in person. Notice the huge body and DB-like bridge and tailpiece.