Agreed on the Caveman. It might be for other people, but $599 is a little more steep than what I'd pay for that particular preamp.
You need this thread:
The Great Preamp/DI Comparison. Be prepared though... it's quite a rabbit hole, but there's a lot of good discussion about preamps from budget to boutique. You might find something there that lights your fire.
That said, it's hard to argue with @Zbysek's suggestion. The Tone Hammer is one of the only preamps I've held onto after quite a few years, and it's great a great DI with a nice warm Aguilar sound. (Most Aguilar stuff I've tried has a pleasant low/low mid warmth to it.) Coincidentally, it's also the pedal that started the Great Preamp thread. Just be prepared with this one, the AGS circuit doesn't seem to be designed to be turned on and off whenever you like. It's more of an on OR off thing, there's a noticeable volume difference when you turn it on that will require making adjustments.
I've also had a Tech21 Q Strip for a few years as well. It's basically the parametric EQ strip from a Neve console (I think?) that will warm your tone a bit, but without imparting "the Sansamp sound."
The Two Notes Le Bass is also a nice suggestion, I've got that one on my "rainy day" list to try someday. But if I were going to pick up a new preamp pedal today, I'd probably opt for the Trickfish Minnow. Designed by Mike Pope who also did Fodera's preamps. Maybe a tad above your price range, but if you can swing the extra cash, it'd probably be worth it. I've got Pope Flexcore preamps in 2 of my basses and they're killer. Jayme Lewis did a pretty in-depth demo of the Minnow (
link here), that has a lot of great info even if you go with a different preamp.
The only Darkglass flavor I haven't tried is the X series... I've owned one of all the others (B3k, B7K, Vintage Ultra, Alpha Omega Ultra), along with the Tone Capsule, Harmonic Booster, and Super Symmetry. Super Symmetry aside, there's definitely a common "Darkglass sound" to all of them just with different flavors of dirt on top. That's probably what @Maxi Funkl is talking about and wanting to avoid.
5sg.