If you have the cash, the Rob Allen basses are IMO as close as you can get. Of course, they aren't going to replace a DB playing a jazz ballad in a good listening room. However, in a relatively loud, busy mix in a live setting, you could never tell the difference out in the audience unless you looked IMO (i.e., by the time you crank up a DB with a pickup through an amp, much of the 'DBness' is lost anyway).
Magnificently made instruments, and if you don't go crazy on fancy tops, etc. the Standard model (the 34" scale 4 string) is amazingly good, and a very good price/value.
IMO and IME!