Those are all Sunn tube amp emulations, if you wanted to emulate a Coliseum Bass amp you would likely have to start with its transistor preamp. I don't have much transistor amp experience, but it's my understanding that those Hartzell era transistor preamps are relatively difficult to reproduce because of multiple odd voltage requirements, and the components and inefficiencies of the era as opposed to modern circuit designs.
Regardless, in ALL cases the preamp alone is <= half of the tone.
That "smooth fuzz" is probably the sum total of the instrument, the integrated amps, and whatever other hardware (speakers, microphone, DI, recording console etc.) is between the bassists hands and your ear.
Depending on your personal interpretation, the term"smooth fuzz" would be in most cases a milder, thicker, non abrasive distortion which would more likely be output stage saturation, or an outboard effect rather than preamp distortion.
