Some of us 'Pros' here at TBDB are not even responding to people that don't fill out a least a little of their Profile I'm not going that far yet, but it would be to your advantage to fill out your profile......at least where you reside. All the better to send you to a luthier in your area...as an example.
Actually, the Underwood is one of the better pick-ups. At least in terms of jazz. I use one mainly because I play a big 5 string antique bass. With the extra 'spread' of the 5 strings, having the two transducers, one on each side of the bridge gives plenty sensitivity to handle all five strings. The Realist is one of the more popular pick-ups, in terms of re-creating the natural sound of your bass. Also it's good with the bow which is a big problem with most pick-ups including the Underwood.
Just out, is the new Revolution "Solo" pick-up which is getting really good reviews.
All the above PU's are good to go without a preamp.
We just had a big poll on pick-ups, ...I think it's under AMP and Pick-ups.
I just checked for you and it's under the Amps and pick-up's Forum heading.
Good luck, fill out your profile, and welcome to TBDB!