I used to use a b2.1u and loved it. It got a bit unreliable after many years of abuse so have just moved on to their new pedal. I used to use the bassman amp sim with the gain setting turned up a bit. Also a bit of compression but with the sensitivity set very low as the compressor on these is a bit over the top IMO . . . . .
I was lucky enough to support Alan Davey's Gunslinger with my own originals band Base Elegance a couple of years ago. He brought his own head but used my cab. We spent ages chatting bass and he had a go on my Rik 4001. Great player and lovely fella :-)
I bought an Ashdown Mi550 from Neil. Communication was prompt accurate and polite. The amp arrived as promised, boxed and in immaculate condition, and well packaged.
Do not hesitate to deal with this guy. One very satisfied customer :-)
Well the pot is there to vary the output of the active circuit to balance it to the volume of the bass if used passive, so I'd very much doubt the box is designed to come out.