Lowend...
Why must there be a catch?
It sounds like what you want is a bridge with individual adjusters for each string, just like on a BG. If so, they do exist, but I have no idea what effect the have on the sound of the bass, or how well they hold up. (I am not a luthier.)
The DB is not a bass guitar and (as I understand it) the bridge does not work the same way. The bass is usually set up with specific strings and playing style in mind. If the strings or playing style change then some changes to the set up, including the bridge and nut are likely to be required.
Now, if you are swapping out one set of steel strings for another, and the guages are similar, then it is possible that nothing needs to be changed. But if you wish to switch to a thick gut from a thin steel (or the reverse) you can expect to need the nut and bridge to be reworked.
As to the relative heights of the strings to the fingerboard, those proportions should have been properly worked into the nut and bridge by the luthier when the set up was done. If they have been then those proportions will usually remain relatively correct, though the entire nut and/or bridge may have to be raised or lowered.
Adjustable bridges were developed to allow for changes in action due to seasonal variation, change of playing style, change in type of string, none of which normally would require an unequal adjustment of the bridge.