I've done my live sound work with a lot of country and americana acts, and some of those dudes are getting into some real botique stuff these days. Things I don't recognize. Of the stuff I do know about
:
A lot of guys are using the Avalon preamp/DI units. I personally think they're overkill for almost all live work unless you've got a seriously high-end system in a very large room. I mean, higher-end than those you'll find in the average quality concert hall. Even then, they don't really do it for all basses.
I've seen a lot of old Ampeg tube heads on small cabinets lately too. You don't need the fridge to get the tone. Not too many new Ampegs. There's a reason for that, I'm sure...
I will tell you however, that the single most popular amp I've run into in this style, for bass players who realize that they don't need to blow the rest of the band off the stage to sound good and be heard is the good ol'
GK MB150S. It's got a surprising amount of power for its size, and it's got tone that rivals some of the big boys, as well as a quality direct XLR out.
I have never had a bass player come across any of my stages with one of these and sound bad. I can't say that for many things. I really wish I played bass at a more-than-dabbling level so that I could justify purchasing one.