I have an Acoustic Image Ten2 combo. The functionality is superb (massively useful high pass filter, phase control, various room-based EQ settings , eg chorus, as well as bass/mid/treb). I have also owned an EA Micro head which I paired with various cabs. I think both are excellent for picking up the subtlety of a double bass sound. Of course neither suits very high volumes (the speakers are the weak point in my view with Acoustic Image) at which point you need PA support anyway.
Currently I am running the Acoustic Image head (taken out of the combo, its meant to be removable) with a Crazy8 cab (made by Tricky Audio in the UK) for small pub/coffee shop type gigs or an EA Wizzy 12 m-line (4 ohm) for louder gigs.
Not sure if that helps. TBH, I reckon an fdeck preamp (with HPF and phase switch) in front of a relatively uncoloured amp (people seem to be recommending the Tecamp Puma 500) would do the trick
Edit: should add that Ed Friedland ("The Bass Whisperer") uses and likes a Genz 6.0-12T combo so you may not really need to change it anyway! See this at 10 minutes [url="https://www.youtube.com/watch?v=sx9OigytbNw"]https://www.youtube.com/watch?v=sx9OigytbNw[/url]